Oxygen infusion module for wastewater treatment

ABSTRACT

This application relates to an oxygen infusion module for a system and method of treating wastewater wherein an oxygen infusion system is used to supersaturate wastewater before aerobic biological processes, wherein oxygen is transferred to the wastewater free of oxygen bubbles and achieves a reduction in power demand for the aeration process of wastewater.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57 andshould be considered a part of this specification.

BACKGROUND Field

This application is related to systems and methods for treatingwastewater (e.g., industrial and/or municipal wastewater) and morespecifically to system and methods of reducing the biochemical oxygendemand (BOD) and chemical oxygen demand (COD) levels in wastewater whileoptimizing energy consumption in aeration systems used in wastewatertreatment systems.

Description of the Related Art

In order to protect the environment and promote public health,communities typically require treatment of municipal, industrial andagricultural wastewater. The discharge of untreated wastewater is notsuitable, since it gives rise to numerous environmental concerns, suchas the pollution of surface and groundwater resources. Untreatedwastewater contains organic matter and nutrients that, if left untreatedand not removed from the waste stream, can result in environmentalpollution. Thus, when untreated wastewater is released into either aboveground bodies of water or subsurface drain fields, the level ofdissolved oxygen in the receiving waters begins to deplete, whichendangers the water bodies themselves, along with the resident plant andaquatic life. Additionally, in developing nations, where potable wateris scarce, it is often desirable to recover as much reclaimable water aspossible from wastewater, rather than disposing of both the wastewaterand the contaminants.

To treat wastewater, communities in highly populated areas commonlycollect wastewater and transport it through a series of undergroundpipes to a large, centralized wastewater treatment plant. However, thereare several problems associated with large, centralized treatmentplants. Centralized wastewater treatment plants are designed and ratedfor processing a specific flow rate of wastewater per day, typicallyexpressed as the rated capacity of the plant, and all treatment plantshave a maximum flow rate capacity. Thus, if a centralized treatmentplant receives more wastewater on a particular day than what the plantwas designed to handle, problems are encountered. For example, when atreatment plant receives larger-than-normal amounts of untreated rawwastewater, treatment performance decreases and partially treated oruntreated wastewater is discharged into a receiving body of water, suchas a river, in order not to exceed the amount of wastewater the plantwas designed to handle. Wastewater treatment systems that canaccommodate surges in capacity are needed.

Wastewater treatment and in particular municipal sewage treatmentusually requires aerobic steps and processes. In these stages themicroorganisms present in the effluent (organic matter) when in contactwith the presence of oxygen, promote reaction in which there is theconversion of the organic matter into carbon dioxide (CO2), water andinert compounds, eliminating the undesirable load. For this to occur,large volumes of oxygen are typically required, which need to be placedin contact with the effluent, in order to guarantee an adequate andstable aerobic environment to achieve the process.

In addition to agitation of the wastewater to create available oxygenfor the biological processes many modern wastewater treatment facilitiesincorporate blown air systems and diffusers to bubble air at pressurethrough the wastewater in the aeration tanks or pools. All theconventional bubble systems, whether large bubble, small bubble, ormicro bubble systems lose up to 90% of the available oxygen to theatmosphere. Conventional aeration systems (e.g., blowers and diffusers)used in wastewater treatment facilities input air that contains fornormal conditions of pressure and temperature only 23% of oxygen, andmuch is lost to the atmosphere as the air bubbles through the wastewaterand exits through the surface of the effluent in the aeration tanks.Additionally, such blower systems typically require large amounts ofenergy, often representing as much as half or more of the total energyconsumption of the facility. The same blower systems may require blowerhouses to accommodate the noise pollution from the fans, as well asexpensive stainless steel distribution systems. The result is thatthough blower systems provide for improved biological processes in theaeration tanks of a wastewater treatment facility, they are alsoinefficient and expensive.

SUMMARY

Therefore, there is a need for an improved system and method to provideoxygen to the aerobic portions of a wastewater treatment process (e.g.,industrial and/or municipal wastewater treatment). In accordance withone aspect of the disclosure, an improved gas infusion system and a moreefficient method for providing oxygen to the biological processes inwastewater treatment advantageously increases the amount of oxygenprovided to the biological processes while simultaneously reducing thetotal energy consumption of the wastewater treatment process.Additionally, the improved gas infusion system advantageously reducesthe system installation, operating, and maintenance costs, while at thesame time providing the capability to facility surges and fluctuationsin capacity.

In accordance with one aspect of the disclosure, a wastewater treatmentsystem (e.g., industrial and/or municipal wastewater treatment) isprovided comprising an oxygen infusion system for transferring oxygen towastewater such that oxygenated wastewater is free of oxygen bubbles.

In accordance with another aspect of the disclosure, a wastewatertreatment system comprises: a wastewater supply; an oxygen generatorconfigured to supply pressurized oxygen at least 90% pure; an oxygeninfusion system comprising; one or more oxygen infusion modulescomprising a plurality of hydrophobic microporous hollow core membranesor fibers; wherein each oxygen infusion module is in fluid communicationwith the oxygen generator, the oxygenator configured to provide a supplyof pressurized oxygen to each membrane in the plurality of hydrophobicmicroporous hollow core membranes or fibers; wherein the oxygen infusionmodule is configured to receive the wastewater supply such that thewastewater surrounds each membrane in the plurality of hydrophobicmicroporous hollow core membranes or fibers; wherein each membrane orfiber of the plurality of hydrophobic microporous hollow core membranesor fibers is configured to allow transfer of the pressurized oxygen tothe wastewater through a plurality of micropores such that oxygentransfer to the wastewater occurs free of oxygen bubbles in thewastewater; and an oxygenated wastewater discharge.

In accordance with another aspect of the disclosure, a method ofoxygenating wastewater for use in aerobic wastewater treatment,comprises: providing a supply of wastewater; generating a supply ofpressurized oxygen using an oxygen generator, wherein the oxygenconcentration is at least 70%; providing an oxygen infusion systemcomprising a plurality of hydrophobic microporous hollow core membranesor fibers in fluid communication with the oxygen generator, wherein eachmembrane further comprises a plurality of micropores having a porepathway diameter of between about 0.01 μm to about 5 μm; providingdirect contact between the pressurized oxygen and the wastewater bytransferring oxygen through the plurality of micropores of the membraneso that the pressurized oxygen enters the wastewater free of oxygenbubbles; transferring oxygen to the wastewater to form a supersaturatedeffluent having a level of oxygen concentration above 60 ppm (e.g.,above 62 ppm) while the dissolved oxygen remained 2-3 ppm in theaeration tank (e.g., biological reactor); discharging the supersaturatedeffluent to an aeration reservoir. Additionally, recirculating or usinga stream of the mixed liquor of the aeration tank itself to besupersaturated advantageously increased control and process benefitsthan supersaturating the raw sewage stream.

Advantages of the present invention include: (1) reduced powerconsumption for increased available oxygen; (2) reduction of wasted airblower power; (3) more efficient oxygenation and use of availableoxygen; (4) reduction of biochemical oxygen demand (BOD); (5) reducedfootprint for blower requirements reducing plant size and capitalexpenditures; (6) flexibility to increase oxygen to meet increaseddemand; (7) modular construction that facilitates expansion of plantcapacity; (8) reduction in sludge produced by the activated sludgeprocess; (9) reduction in chemicals used in the activated sludgeprocess.

In accordance with one aspect of the disclosure, a wastewateroxygenation system is provided. The system comprises an oxygen sourceconfigured to supply pressurized oxygen of at least 70% purity, and noxygen infusion system comprising one or more oxygen infusion modules.Each oxygen infusion module comprises a housing, a plurality ofhydrophobic hollow microporous fibers disposed in the housing, each ofthe hydrophobic hollow microporous fibers having a longitudinal bore anda plurality of micropores on a circumferential wall about thelongitudinal bore. Each oxygen infusion module is in fluid communicationwith the oxygen source so that the plurality of hydrophobic hollowmicroporous fibers receive the pressurized oxygen from the oxygen sourcethrough the longitudinal bore thereof. The oxygen infusion system isconfigured to receive a flow of wastewater from a wastewater supply linesuch that the wastewater flows through each of the one or more oxygeninfusion modules and comes in contact with the circumferential wall ofone or more of the plurality of hydrophobic hollow microporous fibers sothat the pressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater. The oxygenatedwastewater is discharged from the oxygen infusion system via awastewater output connection.

In accordance with another aspect of the disclosure, a wastewateroxygenation system is provided. The system comprises a tank having acover with an inlet opening configured to receive a flow of wastewatertherethrough, and a tank vessel disposed below the cover, the tankvessel having an outlet opening at a distal end of the tank vessel. Thesystem also comprises a plurality of oxygen infusion modules arranged inparallel and disposed in the tank vessel below the cover. Each oxygeninfusion module comprises a housing and a plurality of hydrophobichollow microporous fibers disposed in the housing, each of thehydrophobic hollow microporous fibers having a longitudinal bore and aplurality of micropores on a circumferential wall about the longitudinalbore. Each of the oxygen infusion modules is configured to receive aportion of the flow of wastewater such that the wastewater comes incontact with the circumferential wall of one or more of the plurality ofhydrophobic hollow microporous fibers, and each of the oxygen infusionmodules is configured to receive a flow of pressurized oxygen so thatthe pressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater. The wastewater flowsthrough the plurality of oxygen infusion modules in parallel and thepressurized oxygen flows through the plurality of oxygen infusionmodules in parallel. The oxygenated wastewater is discharged from thetank via the outlet opening in the tank vessel.

In accordance with another aspect of the disclosure, a wastewateroxygenation system is provided. The system comprises a tank having acover with an inlet opening configured to receive a flow of wastewatertherethrough, and a tank vessel disposed below the cover, the tankvessel having an outlet opening at a distal end of the tank vessel. Thesystem also comprises a first array of oxygen infusion modules arrangedin parallel and disposed in the tank vessel below the cover, and asecond array of oxygen infusion modules arranged in parallel anddisposed in the tank vessel, the second array spaced below the firstarray so that the second array is in series with the first array. Eachoxygen infusion module in the first array and the second array comprisesa housing and a plurality of hydrophobic hollow microporous fibersdisposed in the housing, each of the hydrophobic hollow microporousfibers having a longitudinal bore and a plurality of micropores on acircumferential wall about the longitudinal bore. Each of the oxygeninfusion modules is configured to receive a portion of the flow ofwastewater such that the wastewater comes in contact with thecircumferential wall of one or more of the plurality of hydrophobichollow microporous fibers, and each of the oxygen infusion modules isconfigured to receive a flow of pressurized oxygen so that thepressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater. The wastewater flows inparallel through the oxygen infusion modules of each of the first arrayand the second array, the pressurized oxygen flows in parallel throughthe oxygen infusion modules of the each of the first array and thesecond array, and the wastewater flows through the second array after itflows through the first array. The oxygenated wastewater is dischargedfrom the tank via the outlet opening in the tank vessel.

In accordance with another aspect of the disclosure, an oxygen infusionmodule is provided. The module comprises a housing, a central tube thatextends along an axis of the housing, a top plug attached to a proximalend of the housing, and a bottom plug attached to a distal end of thehousing. The module also comprises a plurality of hydrophobic hollowmicroporous fibers disposed in the housing and suspended from a disc andarranged about the central tube. The hydrophobic hollow microporousfibers have a length shorter than a length of the housing, each of thehydrophobic hollow microporous fibers having a longitudinal bore and aplurality of micropores on a circumferential wall about the longitudinalbore. The module also comprises a vent in fluid communication with thecentral tube and with a space inside the housing about the central tube,the vent being configured to vent undissolved oxygen and nitrogen fromthe oxygen infusion module. The oxygen infusion module is configured toreceive a flow of pressurized oxygen from an oxygen source so that theplurality of hydrophobic hollow microporous fibers receive thepressurized oxygen from the oxygen source through the longitudinal borethereof. The oxygen infusion module is configured to receive a flow ofwastewater such that the wastewater flows through the central tube andinto the housing so that it comes in contact with the circumferentialwall of one or more of the plurality of hydrophobic hollow microporousfibers so that the pressurized oxygen is transferred to the wastewaterthrough the plurality of micropores such that oxygen transfer to thewastewater occurs free of oxygen bubbles in the wastewater. Theoxygenated wastewater is discharged from the housing via one or moredistal openings and via the bottom plug.

In accordance with another aspect of the disclosure an oxygen infusionmodule is provided. The module comprises a housing with one or moreopenings on a sidewall of the housing via which wastewater enters thehousing. The module also comprises a plurality of hydrophobic hollowmicroporous fibers disposed in the housing and suspended from a disc,each of the hydrophobic hollow microporous fibers having a longitudinalbore and a plurality of micropores on a circumferential wall about thelongitudinal bore. The oxygen infusion module is configured to receive aflow of pressurized oxygen from an oxygen source so that the pluralityof hydrophobic hollow microporous fibers receive the pressurized oxygenfrom the oxygen source through the longitudinal bore thereof. The oxygeninfusion module is configured to receive a flow of wastewater via theone or more openings in the sidewall of the housing such that thewastewater comes in contact with the circumferential wall of one or moreof the plurality of hydrophobic hollow microporous fibers so that thepressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater. The oxygenatedwastewater is discharged from the housing via a distal end of thehousing.

In accordance with another aspect of the disclosure, a method ofoxygenating wastewater for use aerobic wastewater treatment is provided.The method comprises the step of generating a supply of pressurizedoxygen using an oxygen generator, wherein the oxygen concentration is atleast 70%. The method also comprises the step of supplying thepressurized oxygen to a first oxygen infusion system comprising one ormore oxygen infusion modules. Each oxygen infusion module comprises ahousing, and a plurality of hydrophobic hollow microporous fibersdisposed in the housing. Each of the hydrophobic hollow microporousfibers has a longitudinal bore and a plurality of micropores on acircumferential wall about the longitudinal bore. Each oxygen infusionmodule is in fluid communication with the oxygen generator so that thepressurized oxygen is supplied to the plurality of hydrophobic hollowmicroporous fibers through the longitudinal bore thereof. The methodalso comprises the step of supplying a flow of wastewater to the one ormore oxygen infusion modules such that the wastewater flows through eachof the one or more oxygen infusion modules and comes in contact with thecircumferential wall of one or more of the plurality of hydrophobichollow microporous fibers so that the pressurized oxygen is transferredto the wastewater through the plurality of micropores such that oxygentransfer to the wastewater occurs free of oxygen bubbles in thewastewater to form a supersaturated effluent having a level of oxygenconcentration above 62 ppm. The method also comprises the step ofdischarging the supersaturated effluent to an aeration reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are disclosed in the following detailed descriptionand accompanying drawings.

FIG. 1 is a flow diagram of an example of a prior-art wastewatertreatment system.

FIG. 2 is a flow diagram of a wastewater treatment system.

FIG. 3 is a flow diagram of a wastewater gas infusion system.

FIG. 4 illustrates a side view of a gas infusion module.

FIG. 5 illustrates a longitudinal cross-sectional view of an upperportion of a gas infusion module.

FIG. 6 illustrates a longitudinal cross-sectional view of a lowerportion of a gas infusion module.

FIG. 7 is an isometric view of the bottom end of a barrel and centraltube in the gas infusion module of FIGS. 4 to 6.

FIG. 8 is a flow diagram of a system for gas infusion in a liquid.

FIG. 9 is a schematic side view of a device for housing the microporousmembrane for the transfer of a gas to a liquid.

FIG. 10 is an end view of a portion of a bundle of the microporousfibers used in a gas infusion module.

FIG. 11 illustrates a process for treating wastewater.

FIG. 12 is a performance table and chart illustrating the improvedefficiency and energy consumption under varying capacities and operatingconditions of example implementations of a wastewater treatment systemutilizing infusion of oxygen in a bubbleless process.

FIG. 13 is a side view of an array of gas infusion modules arranged inparallel.

FIG. 14 is a side view of an array of gas infusion modules arranged inparallel and series

FIG. 15 is an isometric cross-sectional view of a gas infusion high flowmodule tank containing multiple internal individual gas infusion modulesbundled together.

FIG. 16 is an isometric view of a gas infusion high flow module tank foruse in a gas infusion system.

FIG. 17 is an isometric cross-sectional view of the gas infusion highflow module tank of FIG. 16 with multiple gas infusion modules.

FIG. 18 is a perspective view of a cover of the gas infusion high flowmodule tank of FIGS. 16-17.

FIG. 19 is a perspective view of a brace used in the gas infusion highflow module tank of FIGS. 16-17.

FIG. 20A is a perspective view of a vessel of the gas infusion high flowmodule tank of FIGS. 16-17.

FIG. 20B is a schematic side view of the vessel in FIG. 20A.

FIG. 21 is a perspective view of a gas infusion module.

FIG. 22 is a schematic of a gas infusion system used in a wastewatertreatment pilot test.

FIG. 23 is a more detailed schematic of the gas infusion system of FIG.22.

FIG. 24 is a chart showing improvement in BOD removal with the gasinfusion system used in the wastewater treatment pilot test of FIGS.22-23.

DETAILED DESCRIPTION

This application relates to systems and methods for wastewater treatment(e.g., industrial and/or municipal wastewater treatment) and morespecifically to improved systems and methods for facilitating biologicalprocesses in wastewater treatment. Advantageously, the systems andmethods described herein facilitate infuse wastewater with oxygen ratherthan air, and the infusion of wastewater with oxygen in a manner free ofbubbles (e.g., in a bubbleless manner) to supersaturate the wastewaterwith oxygen.

The process of treating and reclaiming water from wastewater (e.g., anywater that has been used in homes, such as flushing toilets, washingdishes, or bathing, or water from industrial use, or water fromagricultural facilities, or even water from storm sewers) starts withthe expectation that after it is treated it will be clean enough toreenter the environment.

The quality of the water is dictated by various laws and regulations,for example, the Environmental Protection Agency (EPA) and the CleanWater Act, and wastewater facilities in the U.S. operate to specifiedpermits by the National Pollutant Discharge Elimination System (NPDES).According to the EPA, the Clean Water Act (CWA) establishes the basicstructure for regulating discharges of pollutants into the waters of theUnited States and regulating quality standards for surface waters. Underthe CWA, EPA sets wastewater standards for industry. The EPA has alsodeveloped national water quality criteria recommendations for pollutantsin surface waters. The EPA's National Pollutant Discharge EliminationSystem (NPDES) permit program controls discharges.

As an example of the expected standards, the Biochemical Oxygen Demand(BOD) of average wastewater effluent is 300 mg/L and the effluent aftertreatment is expected to be >30 mg/L. If a wastewater facility does notmeet these expectations, it can risk stiff penalties.

With reference to FIG. 1, a common wastewater treatment process includeseight primary steps, including: (1) bar screening; (2) grit removal; (3)primary clarification; (4) aeration; (5) secondary clarification; (6)chlorination/chemical disinfection; (7) testing and certification; and(8) effluent discharge.

Bar Screening: The physical process of wastewater treatment begins withscreening out large items that have found their way into the sewersystem, and if not removed, can damage pumps and impede water flow. Abar screen is usually used to remove large items from the influent andultimately taken to a landfill. Bar Screening involves the removal oflarge items from the influent to prevent damage to the wastewatertreatment facility's pumps, valves and other equipment.

Grit Removal: Fine grit that finds its way into the influent needs to beremoved to prevent the damage of pumps and equipment downstream (orimpact water flow). Too small to be screened out in the bar screeningstep, this grit needs to be removed from the grit chamber. There areseveral types of grit chambers (horizontal, aerated or vortex) whichcontrol the flow of water, allowing the heavier grit to fall to thebottom of the chamber; the water and organic material continue to flowto the next stage in the wastewater treatment process. The grit isphysically removed from the bottom of the chamber and discarded.

Primary Clarification: After the grit removal step, initial separationof solid organic matter is often applied. Solids known asorganics/sludge sink to the bottom of the primary clarification tank andare pumped to a sludge digestor or sludge processing area (9), dried andhauled away. Proper settling rates are a key indicator for how well theclarifier is operating. Adjusting an influent flow rate into theclarifier can help the operator adjust the settling rates andefficiency.

After grit removal, the influent enters large primary clarifiers thatseparate out between 25% and 50% of the solids in the influent. Theselarge clarifiers (for example tanks) allow for the heavy solids to sinkto the bottom and the cleaner influent to flow. The effectiveness of theprimary clarification is a matter of appropriate water flow. If thewater flow is too fast, the solids don't have time to sink to the bottomresulting in negative impact on water quality downstream. If the waterflow is too slow, it impacts the process up stream.

The solids that fall to the bottom of the primary clarifier are known assludge and pumped out regularly to ensure it does not impact the processof separation. The sludge is then discarded after any water is removedand commonly used as fertilizer.

Aeration: After primary clarification, the influent is pumped to one ormore aeration tanks. Air is pumped into the aeration tank/basin toencourage conversion of NH₃ (ammonia) to NO₃ (nitrate) and provideoxygen for bacteria to continue to propagate and grow. Once converted toNO₃, the bacteria remove/strip oxygen molecules from the nitratemolecules and the nitrogen (N) is given off as N₂↑ (nitrogen gas).Conversion of NO₃ into N₂ (nitrogen gas) occurs in a part of abiological reactor (e.g., an anoxic tank or anoxic zone) where there isno remaining dissolved oxygen inside it.

At the heart of the wastewater treatment process is the encouragementand acceleration of the natural process of bacteria, breaking downorganic material. This begins in the aeration tank. The primary functionof the aeration tank is to pump oxygen into the tank to encourage thebreakdown of any organic material (and the growth of the bacteria), aswell as ensure there is enough time for the organic material to bebroken down. Aeration can be accomplished with pumping and defusing airinto the tank or through aggressive agitation that adds air to thewater. This process is managed to offer the best conditions forbacterial growth. Aerobic bacteria will die if the dissolved oxygenlevels in the wastewater falls below 2 ppm, reducing the efficiency ofthe plant. Levels of dissolved oxygen below 1 ppm results in theprevalence of anaerobic microorganisms instead of aerobicmicroorganisms. The anaerobic microorganisms have a lower efficiency oforganic matter breakdown, reducing the effluent quality as well.Dissolved oxygen monitoring at this stage of the plant is critical.Ammonia and nitrate measurements are common to measure how efficient thebacteria are in converting NH₃ to N₂↑.

A key parameter to measure in wastewater treatment is Biochemical OxygenDemand (BOD). BOD is a surrogate indicator for organic material presentand is used to determine the effectiveness of organic materialbreakdown. BOD is defined as the amount of oxygen demanded by themicro-organisms in the sewage for the decomposition of bio-degradablematter under aerobic condition. This is the most commonly used parameterto determine the strength of municipal or organic quality of the water.The standard BOD test determines the amount of oxygen required by themicro-organisms for the decomposition of the bio-degradable matterpresent in the wastewater sample under 5 days of aerobic condition at atemperature of 20 degree Celsius. It is measured in mg/l.

Chemical Oxygen Demand (COD) is the oxygen demand that is consumed byboth inorganic and organic matter present in the wastewater sample. Thechemical oxygen demand is expressed as the mass of oxygen consumed overthe volume of the solution. Its SI unit is milligrams per liter (mg/l).BOD measures the amount of oxygen required by the aerobic organisms todecompose organic matter and COD measures the oxygen required todecompose organic and inorganic constituents present in the wastewaterby chemical reaction. Hence, the value of COD is greater than BOD.

There are a number of other tests used to ensure optimal organicmaterial breakdown (and BOD reduction) such as measuring pH,temperature, Dissolved Oxygen (DO), Total Suspended Solids (TSS),Hydraulic Retention Time (flow rate), Solids Retention Time (amount oftime the bacteria is in the aeration chamber) and Mixed Liquor SuspendedSolids. Ongoing and accurate monitoring is crucial to ensure the finalrequired effluent BOD.

Secondary Clarification: Treated wastewater is pumped from the aerationtank into a secondary clarifier to allow any remaining organic sedimentto settle out of treated water flow. As the influent exits the aerationprocess, it flows into a secondary clarifier where, like the primaryclarifier, any very small solids (or fines) sink to the bottom of thetank. These small solids are called activated sludge and consist mostlyof active bacteria. Part of this activated sludge is returned to theaeration tank to increase the bacterial concentration, help inpropagation, and accelerate the breakdown of organic material. Theexcess is discarded. The water that flows from the secondary clarifierhas substantially reduced organic material and should be approachingexpected effluent specifications.

Chlorination and Chemical Disinfection: Typically, Chlorine is added tokill any remaining bacteria (or harmful microorganisms) in wastewatereffluent following the secondary clarification. With the enhancedconcentration of bacteria as part of the aeration stage, there is a needto test the outgoing effluent for bacteria presence or absence and todisinfect the water. This ensures that higher than specifiedconcentrations of bacteria are not released into the environment.Chlorination is the most common and inexpensive type of disinfection butozone and UV disinfection are also increasing in popularity. If chorineis used, it is important to test for free-chlorine levels to ensure theyare acceptable levels before being released into the environment.

Testing and Certification: Before effluent is released to theenvironment, most jurisdictions require testing and or certificationthat the treated wastewater meats minimum regulatory standards. Testingfor proper pH level, ammonia, nitrates, phosphates, dissolved oxygen,and residual chlorine levels to conform to the plant's operating permitsare critical to the plant's performance. Although testing is continuousthroughout the wastewater treatment process to ensure optimal waterflow, clarification and aeration, final testing is done to make sure theeffluent leaving the plant meets permit specifications.

Effluent Discharge: After meeting all permit specifications, clean wateris reintroduced into the environment.

Conventional aeration systems used in wastewater treatment facilitiesmay include expensive and inefficient air blowers, diffusers, andmultiple delivery pipes to create bubbles throughout the effluent in theaeration tank. The air is bubbled through the effluent, but onlycontains ambient concentrations of oxygen (approximately 21%). Bubblingair through the effluent loses much of the available oxygen to theatmosphere (e.g., due to the bubbles rising through the effluent andbreaking through the surface of the aeration tank) before oxygen cantransfer to the water due to the small surface area of the largebubbles. In some examples, as much as 90% of the available oxygen in afine bubbler system may escape to the atmosphere.

Another issue with traditional aeration systems relates to the highelectrical demand and cost to operate aeration blowers. Indeed, between25% and 50% of the operational costs of traditional wastewater treatmentfacilities can be attributed to the electrical demand needed across theentire treatment system. And in traditional wastewater treatmentfacilities using activated sludge processes, the aeration system canaccount for between 50% to 70% of the total energy consumed at thefacility.

Seeking to optimize and increase the effluent treatment capacity ofwastewater treatment facilities, including municipal sewage treatmentfacilities, an innovative technology is disclosed herein relating to thetransfer of oxygen to the wastewater influent, thereby replacingtraditional air blower systems needed for the aeration of aerobicprocesses. In this gas infusion oxygenation system and process, gasessuch as dissolved nitrogen and carbon dioxide are removed from theliquid medium, or wastewater effluent and replaced with oxygen, therebycreating a stable oxygenated effluent. By replacing dissolved nitrogen,CO₂, and other gasses with dissolved oxygen (O₂), the effluent reacheslevels of supersaturation, significantly increasing the aeration processcapacity and efficiency.

A gas infusion system described herein can include an oxygen generatorand a gas infusion module (e.g., multiple gas infusion modules) forintroducing oxygen into the wastewater effluent. The oxygen generatorconcentrates oxygen from the atmosphere to levels above ambientconditions and supplies the concentrated oxygen to the gas infusionmodule (e.g., to the multiple gas infusion modules) within the gasinfusion system. Each gas infusion module can include one more hollowtube microporous fibers. The concentrated oxygen is supplied underpressure to the hollow tube fibers or tubes in the gas infusion moduleand the oxygen is diffused or transferred to the wastewater influentwhich surrounds the microporous fibers. The oxygen is transferred to thewastewater influent in a manner free of bubbles (e.g., in a bubblelessmanner) and at oxygen concentration levels above traditional air bloweror bubbler systems, as further described below.

FIG. 2 illustrates a single stage gas infusion unit 200 suitable toreplace a traditional aeration system in a wastewater treatmentfacility. Gas infusion unit 200 may be a modular system and can include:a housing 290, such as a modified 20 foot or 40 foot standard shippingcontainer; a wastewater influent supply connection 291; an oxygenatedwastewater output connection 292, one or more electrical powerconnections 293, a system control 294 (e.g., controller); a wastewaterinfluent supply line 205, a supply feed pump 210, a gas infusion system220 (oxygen infusion system) having one or more oxygen infusion modules225 (e.g., oxygen infusion modules 225 a, 225 b, 225 c), for examplehousing in a housing, such as a tank, and an oxygen source. In oneimplementation, the oxygen source is an oxygen generator 230. In anotherimplementation, the oxygen source is an oxygen supply tank.Advantageously, the gas infusion unit 200 is a standalone unit that canbe transported as a single unit to a wastewater treatment facility,thereby facilitating its transportation and incorporation in awastewater treatment facility. In one implementation, the system control294 (e.g., controller) can control one or both of the flow of oxygenfrom the oxygen generator 230 to the oxygen infusion modules 225 and theflow of wastewater from the wastewater supply line 205 to the oxygeninfusion modules 225.

Wastewater influent is received as input to the gas infusion unit 200from a wastewater treatment facility, such as from a primary clarifyingtank, anaerobic tank, or directly from a bar screening or grit removaltank (not shown). In another implementation, further described below,influent is received as an input to the gas infusion system 200 from anaeration tank of the wastewater treatment facility. Wastewater influententers the gas infusion system 200 through the influent supplyconnection 291 and flows through the wastewater supply line 205 and viathe supply feed pump 210 into the gas infusion system 220.

The oxygen generator 230 supplies oxygen at 70% to 95% purity, forexample 92% purity—significantly greater than atmospheric oxygen levelsof approximately 21% in air supplied from traditional air blower systemsused in wastewater treatment facilities—to the gas infusion system 220via an oxygen supply line 231. Atmospheric air may be collected directlyfrom the surrounding environment by the oxygen generator 230, or may becollected through an air intake 235 and supplied to the oxygen generator230 via an air supply duct 236.

The gas infusion system 220 can include one or more gas infusion modules225 for saturating the wastewater influent with oxygen received by thegas infusion module(s) 225 via the oxygen supply line 231. Each gasinfusion module 225 includes a plurality of hollow tubes or microporousfibers having a plurality micropores with a pore diameter sufficient toallow transfer of the concentrated oxygen to the wastewater influent ina manner free of bubbles (e.g., in a bubbleless manner).

In another implementation, wastewater influent is supplied by influentfeed pump 210 through influent supply line 205 and into an influentmanifold 215, which supports various arrangements of gas infusionmodules 225 from single modules to an array of 2 or more modules (e.g.,2, 3, 4, 5, 6, 7, 8, or more gas infusion modules 225, arranged inparallel) within the gas infusion system 220. The oxygen generator 230supplies concentrated oxygen through the oxygen supply line 231 into agas manifold 223, which supports oxygen supply to each of the gasinfusion modules 225 in the specific array of modules within the gasinfusion system 220.

In another implementation, further discussed below, two or more gasinfusion modules 225 are arranged in series, wherein wastewater influentis supplied by influent feed pump 210 through influent supply line 205and into an influent manifold (not shown), which supports variousarrangements of gas infusion modules 225 arranged in series, such asdepicted 225 a and 225 b in FIG. 2, within the gas infusion system 220.In such an arrangement, oxygen saturated wastewater influent flows fromgas infusions module 225 a and into gas infusion module 225 b where itis further saturated with oxygen. The oxygen generator 220 suppliesconcentrated oxygen through the oxygen supply line 231 into a gasmanifold (not shown), which supports oxygen supply to each of the gasinfusion modules 225 a and 225 b in the specific array of modules withinthe gas infusion system 220.

It will be appreciated that any arrangement of gas infusion modules 225may be provided within gas infusion system 220, from an arrangement ofsingle module use, to multiple modules arranged in parallel (as shown inFIG. 13), to multiple modules arranged in series, and even multiplemodules arranged in a combination of parallel and series (as shown inFIG. 14), depending on the oxygenation needs of the specific wastewatertreatment facility.

In some implementations, two stages of gas infusion can be used tosupersaturate the wastewater with oxygen. The first stage can saturatewastewater influent flowing into an aeration tank with dissolved oxygen.The second stage can saturate mixed liquor from the aeration tank withdissolved oxygen and recirculate the saturated wastewater back to theaeration tank.

In the first stage, oxygen generators collect atmospheric air (withapproximate 21%-23% oxygen) and concentrate oxygen from the collectedair to supply the concentrated oxygen to a gas infusion module(s) incommunication with the wastewater influent. The oxygen generatorsconcentrate oxygen at levels including: concentrated oxygen at levels of90% or more, 80% or more, 70% or more, 60% or more, or at levels greaterthan ambient atmospheric oxygen levels and up to 90% or moreconcentrated oxygen. Concentrated oxygen may be supplied from the oxygengenerator to the gas infusion module(s) at levels of 80%, 81%, 82%, 83%,84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, orgreater than 97% oxygen.

Microporous hollow core fiber membranes, transfer the concentratedoxygen to the wastewater influent. Each microporous hollow fibermembrane includes numerous micro pores that produce a stable interfacefor transferring the oxygen to the wastewater influent without thecreation of bubbles in the influent. Introduction of the concentratedoxygen directly to the influent through the microporous fiber membranesprovides for an oxygen supersaturated fluid without the use or need forair blowers or blower systems as used in traditional aeration systems.

Traditional blower systems are used to create air bubbles in thewastewater to provide available oxygen to the microorganisms. The gasinfusion unit having one or more gas infusion modules transfers oxygento the effluent without the creation of bubbles to provide for a muchmore efficient and higher level of oxygenation of the wastewater. Thisallows longer periods of oxygen retention in the effluent and throughoutthe aeration tanks (or biological reactors) in the wastewater treatmentplant, thereby providing a longer period of oxygen exposure for themicroorganisms in the wastewater aeration (or oxygenation) phase.

Due to the absence of air or oxygen bubbles in the oxygen saturatedwastewater, the dissolved oxygen experiences a Brownian molecularmovement, and the dissolved oxygen is not released because it does notbreak the surface tension of the water. In addition, because the oxygenis dissolved, assimilation of microorganisms is also facilitated byincreasing the process capacity.

By using a direct gas infusion oxygenation system as described herein,where the efficiency of transferring the oxygen to the effluent isgreater than traditional air blower systems, less energy consumptionand, consequently, lower operating costs are advantageously obtained insewage treatment plants. Thus, it becomes possible not only to reducethe operating costs of wastewater treatment plants, but also betterallocate energy resources while providing cleaner water.

In addition, with the increase in efficiency of the gas transferprocesses for the consumption of organic matter from the sewage,expansion of treatment capacity is advantageously possible withoutincreasing the physical size of the wastewater treatment facility.Achieving the ability to treat an increase in flow within the samefootprint of the wastewater facility, also reduces capital expendituresassociated with adding additional wastewater treatment tanks and blowersystems to treat more flow at a wastewater facility due to populationincreases. Similarly, the expansion of capacity may also facilitatetreatment of surge or irregular sewage treatment needs without adding tothe physical plant structure.

In one implementation, a gas infusion system having a wastewater flowcapacity of 1 l/s (one liter per second) was installed as a side streamto an existing wastewater treatment facility. The results from the testfacility demonstrate that:

(1) gas infusion systems consistent with embodiments described hereineliminate the need for expensive, inefficient, and bulky blower aerationsystems;

(2) with the elimination of blower systems, blower houses and otheracoustic accommodations for the blower equipment are not needed;

(3) CPVC (chlorinated polyvinyl chloride) pipes can replace the typicalstainless steel pipes required by blower systems; and

(4) high cost, and maintenance intensive air diffusers, used for theformation of small or microbubbles from the blower supplied air, are notneeded.

Indeed, utilizing high efficiency gas infusion technology as disclosedherein, high efficiency removal of carbonaceous organic matter andnitrification can be achieved with energy reductions that can reachbetween 30% and 90% of that observed in conventional systems. In someimplementations, high efficiency gas infusion devices used as analternative to traditional blower systems in wastewater treatmentfacilities achieve an energy reduction over the traditional system of30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% ormore, 60% or more, 65% or more, or greater than 70% (e.g., 75%, 80%,85%, 90%).

FIG. 3 illustrates one implementation, where two gas infusion systemsare installed in the wastewater stream, the first promoting oxygenationof the wastewater influent from the wastewater treatment facilityentrance (e.g., after primary clarification) and the other promoting theoxygenation of mixed liquor from the aeration tank, which recirculatesback to the aeration tank. In such an arrangement, levels of between 30mg/L of oxygen and 55 mg/L of oxygen in the inlet influent canadvantageously be obtained. In some embodiments, utilizing a gasinfusion unit disclosed herein in the inlet effluent can reach oxygenlevels of: 30 mg/L to 35 mg/L of oxygen; 35 mg/L to 40 mg/L of oxygen;40 mg/L to 45 mg/L oxygen; 45 mg/L to 50 mg/L oxygen; and 50 mg/L oxygenor above (e.g., 55 mg/L of oxygen). Furthermore, utilizing a secondoxygen infusion unit to infuse mixed liquor from the aeration tank andrecirculated to the aeration tank can produce oxygen levels above 55mg/L oxygen in the recirculated effluent stream. In some embodiments,utilizing a gas infusion unit disclosed herein in the mixed liquorstream from the aeration tank can produce oxygen levels in therecirculated effluent stream of 30 ppm to 45 ppm.

The above oxygen saturation levels of the wastewater at the aerationstage of treatment were achieved utilizing a system including: aneffluent recirculation pump, a 60-liter gas infusion pressure chamberwith an array of six gas infusion modules, each having microporoushydrophobic hollow-fiber membranes. The microporous hydrophobichollow-fiber membranes were supplied with 85% to 95% pure oxygen gas(e.g., 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95% pure oxygengas) generated by an external oxygen generator operating at a pressureof 22 Psi. The oxygen feed from the oxygen generator is the gas sourceof the oxygen infusion process that occurs within the gas infusionpressure chamber. It will be appreciated that other oxygen sources maybe utilized in place of an oxygen generator (in the implementationsdescribed herein), including pressurized oxygen from a tank or otherpressure vessel.

As illustrated in FIG. 3, a wastewater treatment system 300 utilizesembodiments of the gas infusion system described herein, and forexample, may include a first metering feed pump or influent feed pump310 to direct a portion of the wastewater plant's primary influent fromthe anaerobic treatment tank or Upflow Anaerobic Sludge Blanket (UASB)303 via influent supply line 305. The influent flow is pumped into thefirst gas infusion system 320 at a rate of, for example, 25-35 litersper minute (1/min or LPM). The first gas infusion system 320 can have agas infusion pressure chamber or housing 321. The influent is circulatedwithin the housing 321 through an eductor (not shown) positioned at thecenter of the six module array of gas infusion units. The eductordirects the influent across the microporous hydrophobic hollow fibermembrane in a co-current manner, or alternatively a countercurrentmanner, allowing for the mass-transfer of oxygen from a gas phase intoan aqueous phase and saturation into the influent, while simultaneouslyachieving a mass-transfer of nitrogen from the aqueous phase to the gasphase where the gaseous nitrogen is vented out of the pressure vesselvia a pressure release valve on the gas infusion pressure chamber 321.

The level of dissolved oxygen achieved within the influent in the gasinfusion pressure chamber 321 is in excess of 100 ppm (e.g., between 100ppm and 330 ppm, inclusive), in excess of 200 ppm, in excess of 300 ppm,and in some embodiments, in excess of 330 ppm. This level ofhighly-oxygenated influent is achieved by dissolving the oxygenmolecules in a substantially bubble-free gas transfer process. As usedherein “bubble-free gas transfer” or “free of oxygen bubbles” means that70% or greater (e.g., 90% or more) of the oxygen dissolved in theinfluent is transferred without the creation of bubbles.

In the embodiment depicted in FIG. 3 a total gas pressure of between 15psi to 22 psi is maintained within the gas infusion pressure chamber 321by restricting the outgoing wastewater flow from the gas infusionpressure chamber 321 to an outflow rate of at least 25 LPM, (e.g., 25LPM, 26, LPM, 27 LPM, 28 LPM, 29 LPM, 30 LPM, 31 LPM, 32 LPM, 33 LPM, 34LPM, or 35 LPM or greater). In some embodiments restricting the outgoingflow may be achieved by providing an outlet pipe (not shown) from thegas infusion pressure chamber 321 with a smaller diameter than the inletpipe 305 diameter from the influent feed pump 310. Alternatively, thetotal gas pressure within the gas infusion pressure chamber 321 may bemaintained between 15 psi and 22 psi, or at levels greater than 22 psiutilizing a small compressor in series with the oxygen generator (notshown) or utilizing a higher capacity or higher pressure oxygengenerator. The outgoing flow rate from the gas infusion pressure chamber321 may be restricted by adjusting one or more metering valves 328 inthe outlet stream.

The first gas infusion system 320 pumps the highly-oxygenated influentfrom the first gas infusion system 320 in a bubble-free manner through asupply pipe 307 that contains an inline dissolved oxygen meter 341, aninline flow meter 342, an inline pH meter 343, and other sensors, suchas pressure and temperature sensors. Data that measures dissolvedoxygen, flow rate, pH and other operating conditions of the highlyoxygenated wastewater from the first gas infusion unit 320 may be fed toa control unit (not shown) and used to adjust and maintain the targetedor desired oxygen levels and flowrates of the highly oxygenatedeffluent. Over-oxygenating the incoming wastewater helps the wastewatertreatment as it facilitates the breakdown of some long chain organiccompounds and also the refractory organic compounds. The data from thevarious sensors can be collected by a programmable logic controller(PLC) that provides real-time data accessible by an automated controlmodule, onsite personal or remote monitoring over a network.

In the example embodiment depicted in FIG. 3, the highly oxygenatedinfluent flows in a continuous manner at a flowrate of between 25 LPMand 35 LMP (inclusive), for example 30 LPM, into the inlet of theaeration tank 350. The aeration tank 350 in the present example may havea volume of approximately 26 cubic meters of wastewater with anoperating retention time of 7.2 hours (considering an inlet flow of 30LPM on average in addition to the recirculation of activated sludge orRAS from the bottom of the clarifier to the aeration tank). The incominghighly-oxygenated wastewater is pumped into the aeration tank 350through an open ended supply pipe 307 whereby the highly-oxygenatedwastewater is released below the surface of the wastewater in theaeration tank 350, for example below the surface by as much astwo-thirds the depth of the tank (e.g., in a 3 meter tall tank, thehighly-oxygenated wastewater is released into the aeration tank 350 at adepth of 2 meters below the surface). Introducing the highly-oxygenatedwastewater well below the surface of the aeration tank promotesagitation and continued suspension of the organic matter in the aerationtank and maintains the saturation of the oxygen in the effluent. Thehighly oxygenated levels of dissolved oxygen are maintained in theaeration tank at a range of 2 ppm to 3 ppm (inclusive) for the purposeof being utilized by the microorganisms in an activated sludge aerobictreatment process where aerobic bacteria in the presence of oxygen,oxidize carbonaceous matter, ammonia nitrogen matter, drive offentrained gases, generate a biological floc that facilitates settlementof suspended solids and generates a mixed liquor with 100-200 ml/L ofsludge after a 30 minute settling test.

Concurrently, effluent from the aeration tank 350 is recirculatedthrough effluent recirculation supply line 361 by recirculation pump 360in a closed loop from the outflow end 351 of the aeration tank 350 andrecirculated to a second gas infusion system 370 for the purpose offurther dissolving additional kilograms of oxygen into the wastewatereffluent stream within the aeration tank 350. The recirculated streamuses recirculation pump 360 to recirculate wastewater effluent into thesecond gas infusion system 370 where the effluent is oxygenated again inthe same manner as described with the first gas infusion system 320.

In this secondary oxygenation process the effluent may achieve adissolved oxygen saturation level in the range of 30 ppm to 45 ppm.

FIGS. 4 to 6 show one implementation of a gas infusion module 400. Thegas infusion module 400 includes a thin-walled, tubular, housing 401(e.g., of stainless steel or another suitable material, such as anothermetal) with an inlet plug 402 in the top end 403 and an outlet plug 404in the bottom end 405 thereof. Flanges 406 and 407 are provided on thetop and bottom ends 403 and 405, respectively, of the housing 401. Theplugs 402 and 404 are sealed in the housing 401 by O-rings 408. Theplugs 402 and 404 are identical, each including a pair of spaced apartflanges 409 and 410 with an annular groove 411 therebetween. The flanges410 act as seats for two-piece clamps 412, which clamp the plugs 402 and404 in and to the housing 401. It will be appreciated that variousmaterial can be used for the gas infusion module components includingPVC (polyvinyl chloride) and CPVC (chlorinated polyvinyl chloride), orother suitable materials.

Concentrated oxygen from an oxygen generator or an oxygen supply tank isintroduced into the top end 403 of the housing via an elbow 413 and aninlet passage 414 in the plug 402. Wastewater is introduced into thehousing 401 via a T-coupling 415 and an inlet passage 416 in the centerof the plug 402. A pressure gauge 417 that is mounted on the T-coupling415 monitors the pressure of wastewater entering the housing 401.

Wastewater entering the inlet passage 416 flows through a short coupler419 into a central tube 420 or core extending substantially the entirelength of the housing 401.

The top end of the coupler 419 is sealed in the plug 402 by o-rings 421.The wastewater is discharged from the tube 420 through four ports 423into the housing 401. A plug 424 in the tube 420 beneath the ports 423prevents the wastewater getting past the ports. The top end of the tube420 extends through and is connected to an epoxy resin disc 425, whichis mounted in the top end of a CPVC sleeve 426. The sleeve 426 is sealedin the housing 401 by an O-ring 428.

A plurality of hollow, microporous fibers 429 of the type described inU.S. Pat. No. 7,537,200, which issued to Craig L. Glassford on May 26,2009, and is incorporated herein by reference in its entirety and forall purposes, extend through and are suspended from the disc 425. Theillustration of the fibers 429 in FIG. 5 is merely schematic. In anexample implementation, an approximately 40 inch long housing 401, mayinclude as many as 5,600 fibers 429, each having a length of 14 inchesand an outside diameter of 0.54 mm. The fibers 429 have a liquidrepellent (e.g., hydrophobic) outer surface. A CPVC barrel 431 ismounted in and extends downwardly from the sleeve 426. The barrel 431 isspaced apart from the housing 401. Openings 432 in the barrel 431 permitwastewater to enter the space between the housing 401 and the barrel431.

The bottom end of the central tube 420 extends through and is supportedby a trefoil base 434 (see FIG. 6), the arms 435 of which are connectedto the open bottom end 436 of the barrel 431. Gaps 437 between the arms435 provide outlets from the barrel 431 for wastewater. Wastewaterdischarged from the barrel 431 passes through an outlet passage 438 inthe bottom plug 404, a coupling 439 and a tube 440 (e.g., ofpolyethylene or other suitable material) to a T-coupling 441. The gassaturated wastewater is discharged through one arm 442 of the coupling441. Undissolved gas from the wastewater entering the coupling 441passes through another T-coupling 443 to a tank 444 for dischargethrough a gas vent valve 445. Opening and closing of the valve 45 iscontrolled by a lever 446 in the tank 444 operated by a float 447.

Undissolved gas in a sump area 452 beneath the fibers 429 passes througha small orifice 453 (see FIG. 6) in the central tube 420 below the areain the barrel 431 containing the microporous tubes 429. The orifice 453acts to control the level of undissolved gas and the wastewater level inthe barrel 431. The orifice 453 also prevents gas from exiting thewastewater outlet passage 439 with the wastewater by venting acontrolled quantity of gas while simultaneously controlling the level ofthe gas/liquid interface in the apparatus. The gas density is lower thanthat of the wastewater and preferentially passes through the orifice453. In testing, it has been observed that the wastewater may not beable to contain all of the gas in solution at this point, and excess gaswhich is not completely dissolved in the wastewater will exit throughthe orifice 453.

Gas entering the central tube 420 through the orifice 453 is dischargedthrough a short coupling 456, which connects the tube 420 to an outletpassage 457 in the bottom plug 404. The gas flows through the passage457, and elbow 458 and a pipe 459 to the third arm 461 of the T-coupling443.

In operation, wastewater from a source thereof enters the gas infusionmodule 400 via the T-coupling 415, inlet passage 416, coupler 419 andthe central tube 420. The wastewater is discharged from the tube throughthe four ports 423 and is distributed over the external surfaces of themicroporous hollow fibers 429. At the same time, gas enters theapparatus via the elbow 413 and the inlet passage 414. The gas flowsinto the open top ends of the microporous hollow fibers 429 while thewastewater is being distributed over the external surface of the fibers429 in a co-current direction with the gas. The wastewater continues tobe in contact with the gas escaping through pores (not shown) in themicroporous fibers 429, whereby the wastewater collects gas intosolution as it travels downwardly in the barrel 431. When the wastewaterexits the area of the barrel 431 containing the fibers 429, it entersthe sump area 452 (see FIG. 6) where excess gas which is not completelydissolved coalesces and collects in the center of the barrel 431. Thegas saturated wastewater is discharged through the outlet passage 439 inthe plug 404, the tube 440 and the T-coupling 441.

When wastewater is initially introduced into the gas infusion module400, the gas infusion module 400 is completely filled with ambient air.The air is vented through the tank 444 and the valve 445 by theintroduction of wastewater into the system. The wastewater rises in thetank 444 to close the valve 445 preventing wastewater from escaping. Theorifice 453 in the central tube 420 maintains equilibrium of thegas/liquid in the area of the microporous fibers 429 and the bottom areaof the barrel 431 which contains higher levels of gas saturation thanthe top of the barrel.

Gas entering the orifice 453 and the valve 445 after the apparatusreaches an equilibrium state leaves wastewater that may contain less gaswhich allows more soluble gas to be infused into the wastewater. The gasoutlet T-coupling 443 allows wastewater collected by the orifice 453 tore-enter the main water outlet stream passing through the coupling 441and vents gas coming out of solution due to turbulence in the wastewateroutlet. Moreover, the T-coupling 443 prevents hydraulic locks in thetank 444 by connecting the tank 444 to the wastewater stream flowingthrough the coupling 441. The tube 440 through which wastewater isdischarged from the apparatus is sized to allow a specific amount ofpressure to be held in the gas infusion apparatus at a specific flowrate. The tube 440 facilitates laminar flow to minimize (e.g.,eliminate) any sheer caused by any restriction caused by the outletpassage 438 and its associated coupling 439. Sheering causes dissolvedgases to come out of solution which is undesirable.

It will be noted that central tube 420, the sleeve 426, the barrel 431and the contents of the barrel can be formed as a module, which can beremoved from the housing 401 by removing the clamps 412 for quickdisassembly (e.g., to facilitate maintenance of the gas infusion module400).

It will further be noted that in some implementations one or more gassescan be introduced to the apparatus (gas infusion module 400) eithersequentially or as a mixed gas. For example, oxygen may be introduced tothe apparatus (gas infusion module 400) followed by introducing nitrogento the apparatus (gas infusion module 400). In such a manner, a fluid orwastewater may be supersaturated with oxygen, held for a desirable timeperiod, and the oxygen may then be displaced by subsequentlysupersaturating the oxygenated fluid with nitrogen.

The microporous structure within each gas infusion module (e.g., themicroporous hollow fibers 429) may include a microporous hydrophobichollow fiber membrane having a pore pathway diameter of about 0.01 μm toabout 5 μm (“micromembrane”). The micromembrane may have a plurality ofpores, wherein the pore pathway diameter is equal to or less than 0.05μm, equal to or less than 0.10 μm, equal to or less than 0.15 μm, equalto or less than 0.20 μm, or equal to or less than 0.25 μm. Microporousstructures and micromembranes are described in U.S. Pat. Nos. 6,209,855and 7,537,200, the entire contents of each of which is herebyincorporated herein by reference for all purposes.

FIG. 8 illustrates an example gas/liquid mixing apparatus, including:

a) a casing 802 having a gas inlet 804, a liquid inlet 806 and agas/liquid mixture outlet 808,

b) a microporous membrane 810 in the casing 802, the microporousmembrane 810 having,

-   -   i) effective, gas/liquid contacting, pore pathway diameters        generally, in the range 0.01 μm to 5 μm, and    -   ii) a side 812 that is repellent to the liquid to be mixed,

the microporous membrane 810 dividing the casing interior 814 into aliquid path, on the water repellent side 812, between the liquid inlet806 and the gas/liquid mixture outlet 808, and a gas chamber from thegas inlet 804,

c) a fluid pressure regulator connected to the casing 802, comprising aliquid back pressure regulator and gauge 818, and a gas pressureregulator and gauge 820, for regulating the gas/liquid pressurerelationship in the casing 802 so that,

-   -   i) the gas pressure does not exceed the liquid pressure, and    -   ii) pressurized liquid does not pass through the membrane        micropores, and

d) a low-liquid-turbulence incurring gas/liquid mixture conveying anddelivery device, in the form of a pipe 829, having a rounded corner andconnected to the gas/liquid mixture outlet 808 and terminating below aliquid level 823 of a tank 824 to gently deliver gas/liquid mixturethereto.

The apparatus may also include gas outlets 805 for removing any liquidthat may collect in the gas chamber 802. The gas outlet 805 is alsouseful for connecting two or more casings 802 in series flow.

The apparatus shown in FIG. 8 may further include a gas valve 821, ahigh pressure oxygen cylinder 822, the open-topped, gas/liquid mixturetank 824, forming a receiving vessel for gas/liquid mixture, a variablespeed liquid pump 826, a liquid pressure regulator and gauge 828, and adissolved oxygen analyzer 830. Gas flow meters 852 and 854 may beprovided together with a gas valve 856. The liquid feed may be suppliedfrom tank 858 and accurately controlled by return line 860 and valve862. In the context of wastewater treatment, tank 858 may be theaeration tank of a wastewater system or the UASB

In FIG. 9, similar parts to those shown in FIG. 8 are designated by thesame reference numerals and the previous description is relied upon todescribe them.

In FIG. 9, the microporous membrane 810 comprises one of a bundle ofhollow, microporous fibers 827, each with a liquid repellent outer side812 and sealed in epoxy resin discs 831 and 832, which, in turn, aresealed in the casing 802 by ‘O’-rings 834 and 836 respectively. Theassembly comprising the bundle of microporous fibers 827 and discs 831and 832, are supported by a central support tube 838 which is sealed inthe casing and spaces the discs 831 and 832 to provide plenum chambers840 and 841. Plenum chamber 840 receives gas from inlet 804, whileplenum chamber 841 passes gas to outlet 805 to the flow meter 854.

The upper ends of the microporous fibers 827 have exposed, open endsabove the disc 831, to the plenum chamber 840.

The lower ends of the microporous fibers 827 have exposed, open endsbelow the disc 832 to the plenum chamber 841.

The central support tube 838 provides the liquid inlet 806 and hasliquid outlet ports 842 to the portion of the interior of the casing 802between the discs 831 and 832.

The gas/liquid mixture outlet 808 is one of two, similar outlets, theother one being designated by reference numeral 809. Both of the outlets808 and 809 are connected to the pipe 829 (FIG. 9).

In other embodiments, either outlet 808 or 809 is used to recirculategas/liquid mixture for further gas enrichment.

In FIG. 10, similar parts to those shown in FIGS. 8 and 9 are designatedby the same reference numerals and the previous description is reliedupon to describe them.

FIG. 10 shows a portion 844 of the hollow, microporous fibers 827 (FIG.9) before they are coiled into the bundle of microporous fibers 827. Themicroporous fibers 827 form the warp of a woven, open mesh structure,with solid fibers 846, of a similar liquid repellent substance to themicroporous fibers, forming the weft.

In operation utilizing the example embodiment of FIGS. 8-10, oxygen gaswas mixed with liquid water, the open-topped tank 824 (FIG. 8) had acapacity of 240 L, and was ^(˜)90 cm×45 cm×60 cm high.

The hollow, microporous fibers 827 (FIGS. 9 and 10) each had an outsidediameter of about 0.54 mm and were made from polyethylene orpolypropylene, both of which are water repellent. The size range of themicropores was controlled in the microporous fiber manufacturing processto produce predetermined, effective pathway diameters, through the wallsof the hollow, microporous fibers. The gas into liquid breakthroughpressure of the microporous membranes was of the order of 40 psi (2.8 kgper cm2). The specific surface area of the bundle of hollow, microporousfibers was about 3,000 square meters per cubic meter of volume.

More specifically, the following Table I gives details of two different,polyethylene fibers used in the tests.

TABLE 1 Fiber εp Do Di I >.07 ~540 ~350 II >0.7 ~380 ~280

εp is the average porosity of the fibers,

Do is the outside diameter of the fibers in microns, and

Di is the inside diameter of the fibers in microns.

The following Table II gives details of bundled fibers used in modulesforming the apparatus shown in FIG. 2 for different tests.

TABLE II Module L No. Dc Dg Fiber I 31 6400 2.667 7.79 I II 31 128002.668 7.79 II III 66 6400 2.667 7.79 I

L is the length of the fibers in cms,

No is the number of fibers in the bundle

Dc is the inside diameter of the bundle, and

Dg is the outside diameter of the bundle.

FIG. 11 illustrates an example embodiment of a process 1000 forutilizing oxygen infusion in wastewater treatment including the stepsof:

(1) providing 1110 an oxygen infusion system comprising: an oxygengenerator and one or more gas infusion modules having a plurality ofmicroporous membranes;

(2) receiving wastewater influent and providing 1115 the wastewaterinfluent to the one or more gas infusion modules as a specified flowrate;

(4) concentrating 1120 oxygen from atmospheric air to levels aboveambient conditions;

(5) providing 1125 the concentrated oxygen to the one or more gasinfusion modules at a pressure to facilitate oxygen transfer to thewastewater influent;

(6) infusing 1130 the wastewater influent with the concentrated oxygenthrough the microporous membrane in a bubble-free gas transfer mannerthat inhibits the formation of oxygen bubbles in the wastewaterinfluent;

(7) discharging 1135 the wastewater influent from the oxygen infusionsystem to an aeration tank of a wastewater treatment facility, whereinthe discharged wastewater has an oxygen saturation of 20 ppm to 30 ppm(inclusive) or higher (e.g., equal to or greater than 30 ppm, between 30ppm and 60 ppm (inclusive), between 50 ppm and 100 ppm (inclusive),between 75 ppm and 150 ppm (inclusive), and equal to or greater than 150ppm); and

(8) maintaining 1140 the wastewater in the aeration tank at dissolvedoxygen levels of 1.5 ppm to 3 ppm, wherein the process of maintainingdesired oxygen levels may be done by a constant feed of oxygenatedwastewater or recirculation of oxygenated wastewater through a secondstage gas infusion unit.

EXAMPLES

Embodiments of the present invention were tested at various flow ratesand pressure conditions to achieve the following results listed in TableIII:

TABLE III Oxygenated Measured Actual O2 Actual BOD PE Flow Flow PE BODPE Demand O2 Supplied BOD outlet Remaining O2 utilized reduction O2Consumption (lpm) (lpm) (mg/L) (mg/L) (mg/min) (mg/L) (mg/min) (mg/min)(mg/min) kgO2/kg BOD 21 7 92.2 1936 931 41 700 231 788 0.293 12 4 1251500 596 56 400 196 604 0.324 16 5 110 1760 605 55 420 185 605 0.306 147 88 1188 696 32 525 171 516 0.331“Industry numbers” for O₂ consumption requirement using conventionalaeration techniques are typically about 1.5 kg O2 per kg BOD consumed.This is far greater than the numbers observed in the tests in Table III(˜0.30) with oxygen infused water. Later tests looked at the reductionof nitrogen (compounds). Based on the ammonia reduction observed inthose later tests and the known O₂ requirement (4.57 kgO2 per kg N), itis estimated that approximately 100 mg/min of dissolved oxygen wasutilized in each of the above runs shown in Table III. This furtherreduces the O₂ consumption to about 0.15 kg per kg BOD, and makes aneven stronger case for using an infused oxygen process.

Efficiencies over traditional air blower systems:

It has been found that significant efficiencies can obtained using thebubble free oxygen infusion system and process of the present inventionto replace traditional aeration systems using air blower devices. Forexample, a conventional wastewater treatment system using blown air mayachieve 1.0 Kg O2/Kg BOD, maintaining 0.5 ppm to 2.0 ppm residualdissolved Oxygen in the aeration tank, while consuming between 12 to 13Kilowatts of power per day. A similar system that replaces the airblowers in the aeration tank with the oxygen infusion system accordingto some embodiments described herein may achieve approximately 0.3 KgO₂/Kg BOD, maintaining 10 ppm to 20 ppm residual dissolved oxygen in theaeration tank, while consuming between 3 to 4 Kilowatts per day ofpower. This represents a tenfold increase in dissolved oxygen whiledecreasing power consumption by as much as 60% or more.

In one implementation, a test wastewater treatment system having a 300L/min capacity using the oxygen infusion system for the aeration of thesewage provided the desired biological efficiency factor ofapproximately 0.3 Kg O₂/Kg BOD, with following parameters: the BOD ofthe influent before oxygenation may be approximately 475 ppm; the BOD ofeffluent from the aeration tank may be approximately 20 ppm; using atotal of 9 gas infusion modules with an influent flow rate to each unitof 150 L/min and an oxygen flow rate to each unit of 4 L/min at apressure of 20 psi resulted in approximately 91% dissolution of theprovided Oxygen, total power usage of approximately 7.75 KW, having atotal oxygen supply rate of approximately 36 L/min, treatingapproximately 18 m³/hr, which further resulted in a power consumptionrate of 0.43 KWH/m³ sewage treated. The oxygen may be supplied forexample, using an Airsep Oxygen Concentrator (Model AS-D100) having acapacity of approximately 40 L/min.

In another implementation, a test wastewater treatment system having a500 L/min capacity using the oxygen infusion system for the aeration ofthe sewage provided the desired biological efficiency factor ofapproximately 0.3 Kg O₂/Kg BOD, with following parameters: the BOD ofthe influent before oxygenation may be approximately 475 ppm; the BOD ofeffluent from the aeration tank may be approximately 20 ppm; using atotal of 15 gas infusion modules with an influent flow rate to each unitof 150 L/min and an oxygen flow rate to each unit of 4 L/min at apressure of 20 psi resulted in a total power usage of approximately 13KW, having a total oxygen supply rate of approximately 60 L/min,treating approximately 30 m³/hr, which further resulted in a powerconsumption rate of 0.43 KWH/m³ sewage treated. The oxygen may besupplied, for example, using an Airsep Oxygen Concentrator (ModelAS-E160) having a capacity of approximately 40 L/min.

FIG. 12 includes a table showing the performance parameters andefficiency measures for various sized systems that incorporate exampleembodiments of gas infusion system described herein. It will beappreciated that available oxygen during aeration of the wastewater isincreased and power consumption is decreased over traditional aerationsystems.

In further example embodiments, various arrangements of the gas infusionmodules within the gas infusion unit may be modified in order tomaximize flow across the microporous membranes while minimizing thepower required to pump the wastewater effluent through the gas infusionunit. Gas infusion modules may be arranged in series, parallel, acombination of in series and in parallel, or bundled in specificgroupings with common housings to provide optimized efficiency.

FIG. 13 illustrates an example of a multi-unit array 1310 of gasinfusion modules arranged in parallel. As depicted, the multi-unit array1310 includes multiple gas infusion modules 1315, each comprising ahousing, connections for the inflow and outflow of wastewater andconcentrated oxygen, and an arrangement of microporous, hollow corefibers, as described in FIGS. 4 through 7, and elsewhere in thisdisclosure. Array 1310 further comprises a wastewater inlet 1320 forproviding wastewater to the array. Inlet 1320 is in communication withsupply pipe 1332 which feeds wastewater to each infusion module 1315.Supply pipe 1332 may be in direct connection between any two or moreinfusion module 1315, connecting each infusion module 1315 in series.Alternatively, supply pipe 1332 may be replaced with a manifoldconnecting each infusion module 1315 in series. Array 1310 furthercomprises discharge pipe 1324 for carrying the oxygen infused wastewaterfrom the infusion modules 1315 and away from array 1310 via wastewateroutlet 1326. Discharge pipe 1324 may be in direct connection between anytwo or more infusion module 1315, connecting each infusion module 1315in series. Alternatively, discharge pipe 1324 may be replaced with amanifold connecting each infusion module 1315 in series. Not shown inFIG. 13 is the oxygen connection or gas discharge as describedpreviously in this disclosure. The example embodiment of array 1310included fifteen infusion modules in parallel. It will be appreciatedthan any number of modules 1315 in a single array 1310 arranged inparallel are contemplated herein, from to two modules to fifty or more.The number of modules depends on the required oxygen infusion levels andpumping capability of the targeted wastewater treatment facility.

FIG. 14 illustrates an example of a multi-unit array 1410 of gasinfusion modules comprising a first array 1440 with individual modulesarranged in parallel as described with respect to the array in FIG. 13and a second array 1445 also with individual modules arranged inparallel as described with respect to the array in FIG. 13. First array1440 and second array 1445 are together arranged in series with theoutlet 1426 of first array 1440 leading to the inlet 1421 of secondarray 1445. The multi-unit array 1410 of gas infusion modules depicts atwo stage infusion process where wastewater is infused with oxygen in afirst stage thorough first array 1440 and then infused again withadditional oxygen in a second stage 1445, such that before wastewater isdischarged from the multi-unit array 1410 it has flowed through two setsof infusion modules 1415 a and 1415 b. The illustrated implementationprovides for multiple infusion module units arranged in parallel toprovide for volume of processing with a second array in series with thefirst, wherein the second array also has multiple infusion modulesarranged in parallel to provide for volume of processing. As depicted,the multi-unit array 1410 includes multiple gas infusion modules 1415 aand 1415 b, each comprising a housing, connections for the inflow andoutflow of wastewater and concentrated oxygen, and an arrangement ofmicroporous, hollow core fibers, as described in FIGS. 4 through 7, andelsewhere in this disclosure. First array 1440 further comprises awastewater inlet 1420 for providing wastewater to the array. Inlet 1420is in communication with supply pipe 1422 which feeds wastewater to eachinfusion module 1415 a. First array 1440 further comprises dischargepipe 1424 for carrying the oxygen infused wastewater from the infusionmodules 1415 a and away from first array 1440 via wastewater outlet1426. First array 1440 provides a first stage for gas infusion.Oxygenated wastewater from outlet 1426 flows through transfer pipe 1427and into inlet 1421 of second array 1445.

Second array 1445 further comprises a wastewater inlet 1421 forproviding wastewater to the second array. Inlet 1421 is in communicationwith supply pipe 1423 which feeds wastewater to each second stageinfusion module 1415 b. Second array 1445 further comprises dischargepipe 1425 for carrying the oxygen infused wastewater from the infusionmodules 1415 b and away from multi-unit array 1410 via wastewater outlet1427. Second array 1445 provides a second stage for gas infusion.Oxygenated wastewater from outlet 1427 flows out of the multi-unit array1410 and typically into an aeration holding pond, tank or pool.

The example embodiment of array 1410 includes twelve infusion moduleswith the first six infusion modules arranged in parallel and the secondsix also arranged in parallel, wherein the first six modules are inseries with the second six modules such that wastewater flows through atleast one module in the first grouping of modules and at least onemodule in the second grouping of modules. It will be appreciated thanany number of modules 1415 in a single array 1440 or 1445 arecontemplated herein, from one or two modules to fifty or more. It willfurther be appreciated that more than two arrays may be arranged inseries, such as 3, 4, 5 or more arrays, each containing any number ofmodules arranged in parallel. The number of modules depends on therequired oxygen infusion levels and pumping capability of the targetedwastewater treatment facility to reach a the desired objective ofwastewater supersaturated with oxygen while minimizing the electricaldemand for pumping the water and aerating the effluent.

Not shown in FIG. 14 is the oxygen connection or gas discharge asdescribed previously in this disclosure.

FIG. 15 shows a gas infusion tank 1515 (e.g., high flow module tank)with a cover 1510 and a housing 1517 (a tank vessel) that may containmultiple gas infusion modules 1550, each having an arrangement of themicroporous, hollow core fiber bundles as described in FIGS. 4 through7, and elsewhere in this disclosure (e.g., the gas infusion module 1700described below). Each gas infusion module 1550 may contain between oneand forty or more fiber bundles, such that wastewater is provided to thegas infusion tank 1515 to envelop the multiple gas infusion modules 1150within the housing 1517, advantageously reducing the number ofconnections and piping losses (e.g., as compared to the gas infusionmodule 400 in FIGS. 4-7, due to the absence of components such as theelbows 413 and 458, inlet plug 402, outlet plug 404, etc.). Though notshown in FIG. 15, oxygen can be provided through the fiber bundles, in aco-current manner with the wastewater introduced into the infusion tank1515, so that oxygen is transferred via the fiber bundles in manner feeof bubbles to the wastewater to supersaturate the wastewater withoxygen. Wastewater can enter the infusion tank 1515 via the opening 1512(inlet opening) at the top of the infusion tank 1515 and can exit theinfusion tank 1515 via the opening 1522 (outlet opening) at the bottomof the tank 1515. In one implementation, wastewater can flow from theopening 1522 to an opening 1512 of another gas infusion tank 1515,thereby providing for a gas infusion system where gas infusion tanks1515 are arranged in series and wastewater flows through the gasinfusion tanks 1515 in series, and flows through each of the gasinfusion modules 1550 in each gas infusion tank 1515 in parallel.

FIGS. 16-17 show a gas infusion tank 1600 (e.g., an inline saturator orILS, a high flow module tank) with a plurality of gas infusion modules1700 arranged in parallel. For clarity and to show certain structure ofthe gas infusion tank 1600, some of the gas infusion modules 1700 arenot shown in the as infusion tank 1600 of FIG. 17. The gas infusion tank1600 (e.g., multiple gas infusion tanks 1600, for example connected inparallel) can be incorporated into a gas infusion unit (e.g., such as astandalone gas infusion unit similar to the gas infusion unit 200described above in connection with FIG. 2). For example the gas infusiontank 1600 (e.g., multiple gas infusion tanks 1600 connected in parallel)can replace the gas infusion system 220 in FIG. 2. Accordingly, thecomponents and description above for the gas infusion unit 200 isunderstood to apply to a system incorporating the gas infusion tank 1600(e.g., multiple gas infusion tanks 1600 connected in parallel) in astandalone unit.

The gas infusion tank 1600 has a cover 1610 and a tank vessel 1620 towhich the cover 1610 can be coupled (e.g., via flanges F on both thecover 1610 and the tank vessel 1620). The cover 1610 has an opening 1612via which wastewater can enter the gas infusion tank 1600, a pressuregauge 1614 attached to a port 1613 (see FIG. 18) and a coupling 1615(see FIG. 18) via which oxygen (e.g., from an oxygen generator or oxygentank) can be introduced into the gas infusion tank 1600. In oneimplementation, the port 1613 can be a ¼ inch gauge port. In oneimplementation, the coupling 1615 can be a ¾ inch coupling (e.g.,stainless steel coupling). In one implementation, the tank vessel 1620can have a height to approximately 52 inches.

With reference to FIG. 17, the gas infusion tank 1600 has (in order) anupper plenum chamber 1602, a first array 1605 of gas infusion modules1700, an intermediate chamber 1603, a second array 1606 of gas infusionmodules 1700 and a lower plenum chamber 1604. As discussed above,wastewater enters the gas infusion tank 1600 via the opening 1612, andwastewater exits the gas infusion tank 1600 via siphon break or tube1670 and opening 1622. In one implementation, the opening 1622 can beapproximately 38 inches from the flange F of the tank vessel 1620. Thetank vessel 1620 has a drain 1624 via which the tank vessel 1620 can bedrained of liquid. The drain 1624 can be located a distance H1 from theflange F of the tank vessel 1620, as shown in FIG. 20B. In oneimplementation, the distance H1 can be about 48 inches. In oneimplementation, the tank vessel 1620 has an inner diameter of 36 inches(e.g., about 1 m), but can have a different diameter in otherimplementations. In one implementation, the first array 1605 and thesecond array 1606 can each have 150 gas infusion modules 1700. However,in other implementations, the first array 1605 and the second array 1606can have a different number of gas infusion modules 1700 (e.g., greaterthan 150 modules or smaller than 150 modules). In anotherimplementation, the gas infusion tank 1600 only has the first array 1605of gas infusion modules 1700 and excludes the second array 1606 of gasinfusion modules 1700.

With reference to the first array 1605 of gas infusion modules 1700, thegas infusion modules 1700 are disposed between a first plate 1635 and asecond plate 1637, the first plate 1635 having openings 1636 and thesecond plate 1637 having openings 1638 that align with each other. Eachof the gas infusion modules 1700 is disposed between and aligned withone of the openings 1636 in the first plate 1635 and one of the openings1638 in the second plate 1637. A plate 1630 is spaced above the firstplate 1635 (e.g., by spacers between the plate 1630 and the first plate1635, such as protrusions on an underside of the plate 1630) to define agap G1 between the plate 1630 and the first plate 1635. A cross brace1650 (see FIG. 19) is located under the second plate 1637 and supportsthe first array 1605 of gas infusion modules 1700. The cross brace 1650has a pair of arms 1652 that cross each other and a recess 1654 (e.g.,pair of recesses 1654) on a bottom edge of the cross brace 1650

With reference to the second array 1606 of gas infusion modules 1700,the gas infusion modules 1700 are disposed between a third plate 1645and a fourth plate 1647, the third plate 1645 having openings 1646 andthe fourth plate 1647 having openings 1648 that align with each other.Each of the gas infusion modules 1700 is disposed between and alignedwith one of the openings 1646 in the third plate 1645 and one of theopenings 1648 in the fourth plate 1647. A plate 1640 is spaced above thethird plate 1645 (e.g., by spacers between the plate 1640 and the thirdplate 1645, such as protrusions on an underside of the plate 1640) todefine a gap G2 between the plate 1640 and the third plate 1645. A crossbrace 1650 (see FIG. 19) is located under the fourth plate 1647 andsupports the second array 1606 of gas infusion modules 1700. The recess1654 has a contour that generally matches the contour of the tube 1670over which the cross brace 1650 is positioned.

With continued reference to FIG. 17, the plate 1640 is spaced from thesecond plate 1637 to define the intermediate chamber 1603 therebetween.The intermediate chamber 1603 is sized to inhibit (e.g., prevent)turbulence of flow to minimize (e.g., avoid) oxygen coming out ofsolution in the infused wastewater. The plate 1630 has a central openingO1, and the plate 1640 has a central opening O2. A fitting 1680 iscoupled to the plate 1630 to provide fluid communication with the gapG1. A tube, hose or pipe (not shown) can couple to the fitting 1680 andan underside of the coupling 1615 to provide a flow path via whichoxygen (e.g., from an oxygen generator or oxygen tank) can be introducedinto the gap G1 and thereby the gas infusion modules 1700 of the firstarray 1605. Advantageously, the gap G1 allows the equalization ofpressure for the oxygen injected into the gap G1 so that the gasinfusion modules 1700 of the first array 1605 are provided with oxygenat the same pressure and flowrate. Additionally, delivery of oxygen viathe gap G1 (e.g., as compared with the structure, for example elbow 413and plug in the gas infusion module 400 of FIGS. 4-7) simplifies thedelivery of oxygen to the plurality of gas infusion modules 1700 andreduces the number of connections and losses (e.g., due to piping thatis excluded by using the gap G1 to distribute oxygen delivery to the gasinfusion modules 1700).

Though not shown, a fitting (similar to the fitting 1680) is coupled tothe plate 1640 to provide fluid communication with the gap G2. A tube,hose or pipe (not shown) can couple to the fitting and a coupling 1628in a sidewall of the tank vessel 1620 (see FIGS. 20A-20B) to provide aflow path via which oxygen (e.g., from an oxygen generator or oxygentank) can be introduced into the gap G2 and thereby the gas infusionmodules 1700 of the second array 1606. Advantageously, the gap G2 allowsthe equalization of pressure for the oxygen injected into the gap G2 sothat the gas infusion modules 1700 of the second array 1606 are providedwith oxygen at the same pressure and flowrate. Additionally, delivery ofoxygen via the gap G2 (e.g., as compared with the structure, for exampleelbow 413 and plug in the gas infusion module 400 of FIGS. 4-7)simplifies the delivery of oxygen to the plurality of gas infusionmodules 1700 and reduces the number of connections and losses (e.g., dueto piping that is excluded by using the gap G1 to distribute oxygendelivery to the gas infusion modules 1700).

Oxygen can be provided to the coupling 1615 and the coupling 1628 by thesame source (e.g., oxygen generator or oxygen tank). In oneimplementation, a flowmeter can be in fluid communication with thecoupling 1615 and the coupling 1628 to independently regulate the flowof oxygen through the couplings 1615, 1628 (e.g., so that the oxygeninjected through the coupling 1628 is at a pressure about 1 psi greaterthan the oxygen injected through the coupling 1615). The flowmeters canoptionally be controlled by a controller (e.g., a microcontroller unitor MCU, a computer processor, etc.),

In operation, wastewater enters the upper plenum chamber 1602 of the gasinfusion tank 1600 via the opening 1612 and passes through the openingO1 in the plate 1630 and along a flow path F1 into a space above thesecond plate 1637. The wastewater liquid level rises in said space abovethe second plate 1637, as the wastewater flows around all of the gasinfusion modules 1700 in the first array 1605, until it reaches theopenings of the gas infusion modules 1700, as further discussed below,and the wastewater flows into the gas infusion modules 1700. While thewastewater flows through the gas infusion modules 1700 of the firstarray 1605, the wastewater is infused with oxygen, which is introducedinto the top of the gas infusion modules 1700 via the gap G1. Thestructure of the gas infusion module 1700 is further described below.The wastewater infused with oxygen exits the gas infusion modules 1700of the first array 1605 via the openings 1638 in the second plate 1637and into the intermediate chamber 1603.

Once in the intermediate chamber 1603, the wastewater passes through theopening O2 in the plate 1640 and along a flow path F2 into a space abovethe fourth plate 1647. The wastewater liquid level rises in said spaceabove the fourth plate 1647, as the wastewater flows around all of thegas infusion modules 1700 in the second array 1606, until it reaches theopenings of the gas infusion modules 1700, and the wastewater flows intothe gas infusion modules 1700. While the wastewater flows through thegas infusion modules 1700 of the second array 1606, the wastewater isinfused with oxygen, which is introduced into the top of the gasinfusion modules 1700 via the gap G2. The wastewater saturated withoxygen exits the gas infusion modules 1700 of the second array 1606 viathe openings 1648 in the fourth plate 1647 and into the lower plenumchamber 1604. The wastewater (saturated with oxygen via the first array1605 and second array 1606 of gas infusion modules 1700) exits the lowerplenum chamber 1604 via the tube 1670 and opening 1622.

With continued reference to FIGS. 16-17 and 20A, undissolved gas fromthe saturated wastewater (e.g., undissolved oxygen, excess nitrogenremoved from the wastewater due to the infusion of oxygen in thewastewater) can pass through a T-coupling 1674 to a vent 1676. Said gascan pass through the hose 1672 as the saturated wastewater exits theopening 1622 and/or can pass through fitting 1626 in the tank vessel1620 (see FIG. 20A) to which the T-coupling 1674 couples. The fitting1626 can in one implementation be located on the tank vessel 1620 so itis a vertical location that coincides with a location just below theopenings of the gas infusion modules 1700. The location of the fitting1626 provides the liquid level for the wastewater in the tank vessel1620. In one implementation, the fitting 1626 can have a diameter of 2inches and be approximately 23½ inches from the flange F of the tankvessel 1620.

The gas infusion tank 1600 provides for a series parallel arrangementfor gas infusion (e.g., oxygen infusion) of wastewater. The wastewaterflows in parallel through the gas infusion modules 1700 of each of thefirst array 1605 and second array 1606. Additionally, the wastewaterflows in series from the first array 1605 to the second array 1606. Theseries parallel arrangement advantageously improves the performance ofthe gas infusion tank 1600 because additional infusion of the wastewaterwith oxygen is achieved, as compared with a gas infusion tank that onlyhad one array of gas infusion modules 1700. Additionally, the gasinfusion tank 1600, as compared to the gas infusion module 400 in FIGS.4-7, has a simplified architecture for delivering oxygen to the gasinfusion modules 1700 of the first array 1605 and the second array 1606that avoids having to individually feed oxygen to each of the gasinfusion modules 1700 via separate fitting and tubes, thereby reducingtime and materials needed to assemble the system, as well as reducing(e.g. eliminating) possible failure points due to the use of multiplefittings and hoses, which are not needed in the gas infusion tank 1600.Further, because the wastewater passes in series through the first array1605 and the second array 1606 of the gas infusion modules 1700 (e.g.,two passes through gas infusion modules), the gas infusion tank 1600excludes the use of a recirculation pump since it does not need torecirculate wastewater through an array of gas infusion modules toachieve multiple passes through the gas infusion modules (e.g., twopasses are already achieved by flowing wastewater through the firstarray 1605 and the second array 1606).

In one implementation, the gas infusion tank 1600 can be operated at amaximum flowrate of wastewater of approximately 1700 LPM at 20 psi and amaximum flowrate of oxygen of 315 LPM (e.g., to supersaturate thewastewater with oxygen). The oxygen would be delivered at substantiallythe same pressure (e.g., about 0.5 psi higher than the liquid pressure)to facilitate the transfer of oxygen to the wastewater within the gasinfusion modules 1700 (e.g., and to inhibit or prevent the wastewaterfrom breaking the surface tension of the pores in the fibers of the gasinfusion module 1700 and flood the fibers). In another implementation,the gas infusion tank 1600 can be operated at a maximum flowrate ofwastewater of approximately 1700 LPM at 30 psi and a maximum flowrate ofoxygen of 400 LPM (e.g., to supersaturate the wastewater with oxygen).

FIG. 21 shows a schematic view of one of the gas infusion modules 1700,which has a housing 1710 with one or more openings 1712 (e.g., a pair ofopenings on opposite sides of the housing 1710). The gas infusion module1700 has a height H2 and houses multiple fibers 1720. The fibers 1720can be similar to (e.g., identical to) the fibers 429 of the gasinfusion module 400 in FIGS. 4-7. The fibers 1720 can in oneimplementation be a 540 micron microporous hollow fiber (ofpolyethylene) with an outer diameter of about 0.5 mm, a wall thicknessof 95 microns that defines a central bore (e.g., channel, pathway) ofeach of the fibers 1720 and about 75% porosity with a nominal pore sizeof about 0.1 microns. The fibers 1720 can be weaved together with solidhydrophobic fibers or rods, in a similar manner as shown in FIG. 10, toform a warp of a woven, open mesh structure, or a mat (e.g., tofacilitate or improve contact between the wastewater and the fibers1720). The mat can then be rolled and inserted into the housing 1710. Inone implementation, eight fibers 1720 are weaved together to make themat. In one implementation, the mat can have a length of about 30 inches(in the direction of the fibers 1720) and a width of about 24½ inches.In another implementation, the fibers 1720 can be a 270 micronmicroporous hollow fiber with an outer diameter of about 0.25 mm. In oneimplementation, the length of the fibers 1720 in the gas infusionmodules 1700 is between about 9 inches and about 13 inches, such asabout 10 inches. The fibers 1720 can be held in the housing 1710 by adisc (e.g., an epoxy resin disc similar to resin disc 425 in the gasinfusion module 400 in FIGS. 4-7).

In one implementation, the housing 1710 has an inner diameter of about 2inches and the number of fibers 1720 in the housing 1710 is 3200, thefibers 1720 (and the housing 1710) having a length of 10 inches. Thefibers 1720 have a packing factor in the housing 1710 of about 38% (e.g.38% of the space in the housing 1710 is taken up by the fibers 1720).The gas infusion module 1700 can be operated at a wastewater liquid flowof 18 LPM at 20 psi and an oxygen flow of 1.2 LPM at a 92% purity.

The gas infusion tank 1600 (e.g., inline saturator) with the gasinfusion modules 1700 as described above can be used in a gas infusionsystem to infuse wastewater with oxygen in a manner that advantageouslyimproves the efficiency of the wastewater treatment plant byapproximately 50%. Below are example calculations for the operation of agas infusion system utilizing the gas infusion tank 1600 incorporatingthe gas infusion modules 1700 as described above.

Table IV below shows design parameters for a waste water treatment plant(WWTP).

TABLE IV Waste Water Treatment Plant (WWTP) Operating Parameters InletWWTP BOD inlet 216 ppm BOD outlet 20 ppm TKN input 60 ppm TKN outputfrom UASB 60 ppm Water flow WWTP (PER TRAIN) 60 lps 3600 1 pm BiologicalEfficiency Factor 1.00 kg 02/kg BOD Enter % dissolution efficiency 90.00% expected Oxygen concentrator-PSA or VSA VSA 13.29 kw/h Blowerefficiency (Conventional) 10.40% % Feed pump rated efficiency   90% %

Table V below shows the design parameters for one of the gas infusionmodules 1700.

TABLE V Design Parameters for 1 Gas Infusion Module Design Parameters (1module) There are 1600 fibers in a 30″ single sheet. # of full-lengthfolded partial sheets used 2 Total # of fibers 3200 Packing Factor 38.09% (Max 38%) # of sheets used 0.71 sheets CoreOD 0.000 inch 0 cm Shell ID2.00 inch 5 cm Fiber length 10.000 inch 25 cm Temp 20 (C) Inlet water doconcentration 0 ppm Desired oxygen flow to each 1.2 lpm 1200 sccmDesired water flow each 18.00 (LPM) PO2 20.00 psig 34.70 psia Oxygenconcentration 92.00 % 0.92 Flooded inlet to pump 4.5 meters 6.34 psig

Table VI below shows the outlet performance for one of the gas infusionmodules 1700.

TABLE VI Outlet Performance for 1 Gas Infusion Module Outlet Performance(1 module) Outlet ppm 67.517 ppm Sat’ P(psi) 22.855 psi 8.2 psig?? %sat’d 55.690 % kg/day O2 1.750 kg/day O2 dissolved each 0.9 lpm 850.71sccm Module dissolution efficiency 78.89 % kg O2/d · m2 1.277 Watervelocity 24.691 cm/s “Min. press, req. for dissolution 20.30 psi 14.28h(m) Water flow to each unit 18.0 lpm Oxygen flow to each unit 1.2 lpm

Table VII below shows the outlet performance for the wastewatertreatment plant (WWTP).

TABLE VII Outlet Performance for Wastewater Treatment Plant (WWTP)Output WWTP system (US) PPM 60.76 mg/l Oxygen delivered (each) 1.75kg/day Oxygen delivered (each) 1.58 kg/day Total kg/day dissolvedrequire 1,038 kg/day 43 kg/h Total # of fiber insets 659 inserts 470.9sheets Total amount of water 11867.62 lpm 712.06 m3/h recirculated×times the inlet flowrate 3.30 ×inlet flow Total kg02/day dissolved1038.44 kg/day 43.27 kg/hr Total ipm oxygen required 791.17 1pm 1139.29m3/d Recirculation pump power 20.62 kw 28.05 hp Oxygen generation 13.29kw 18.08 hp Total power usage 33.91 kw Oxygen supply rate 791.17 1pmm3/hr sewage treated 216.00 m3/hr 5184 m3/day kWh/m3 infusion with 0.16kwh/m3 gas infusion system disclosed herein kWh/m3 Conventional 0.33kwh/m3 Oxygen requirements 0.93 kg 02/kg (calculated) BOD Oxygen usageefficiency 1.28 kg02/kwh

Table VIII below shows the design parameters for the gas infusion systemusing the gas infusion tank 1600 (inline saturator or ILS) with the gasinfusion modules 1700 as described above to meet the output performancefor the wastewater treatment plant (WWTP).

TABLE VIII Inline Saturator Design ILS multimodule design # of fiberinserts per ils 150 Total number of ILS units required 4.4 ILS unitsAmount of water to each ILS 2700 lpm

As shown in Tables IV to VIII, in order to meet the output performanceof the wastewater treatment plant (WWTP), the gas infusion system needsat least 4.4 ILS units or gas infusion tanks 1600, or five gas infusiontanks 1600. The five gas infusion tanks 1600 can be part of a standalonegas infusion system or unit, similar to the gas infusion unit 200 inFIG. 2, where the five gas infusion tanks 1600 can be operated inparallel. The calculations show that such a gas infusion system or unitusing the gas infusion tanks 1600 and gas infusion modules 1700described herein would advantageously achieve a reduction in power useor improvement in efficiency of at least 50% (e.g., 0.16 kWh/m3 for thegas infusion system versus 0.33 kWh/m2 for the conventional air blowersystem). Higher efficiencies can be achieved where the biologicalefficiency factor is smaller than 1.00 Kg O₂/Kg BOD.

FIGS. 22-23 show a schematic diagram of a wastewater treatment system1800 pilot test utilizing gas infusion modules and gas infusion systemsor units in accordance with one or more embodiments described above(e.g., gas infusion unit 200 in FIG. 2, gas infusion modules 400 inFIGS. 4-7). FIG. 22 shows a more simplified schematic diagram and FIG.23 shows a more detailed schematic diagram. FIG. 24 shows a chartshowing improvement in BOD removal with the gas infusion system used inthe wastewater treatment pilot test of FIGS. 22-23.

The system 1800 includes a first gas infusion unit or first inlinesaturator 1810 and a second gas infusion unit or second inline saturator1820. The first inline saturator 1810 and the second inline saturator1820 can be similar to gas infusion units or inline saturators describedabove (e.g., the gas infusion unit 200 in FIG. 2) that utilize gasinfusion modules described above (e.g., the gas infusion modules 400 inFIGS. 4-7).

The first inline saturator 1810 receives wastewater from a pipe betweenan anaerobic treatment tank or Upflow Anaerobic Sludge Blanket (UASB)and an aeration tank of the wastewater treatment plant, as shown in FIG.23. The first inline saturator 1810 infuses the wastewater with oxygen(e.g., in the manner described above by transferring oxygen towastewater using the fibers in the gas infusion module(s)), and deliversthe oxygen saturated wastewater to a biological reactor 1830 (e.g., alsoreferred to an aeration tank in wastewater treatment plants). Wastewateris recirculated from the biological reactor 1830 via a pump 1840 to thesecond inline saturator 1820. The second inline saturator 1820 infusesthe recirculated wastewater with oxygen (e.g., in the same manner as thefirst inline saturator 1810), and delivers the oxygen saturatedwastewater to the biological reactor 1830. Wastewater is transferredfrom the biological reactor 1830 to a clarifier tank 1850. A portion ofthe wastewater flow is recirculated from the clarifier tank 1850 to thebiological reactor 1830 via a recirculation pump 1860, and effluent isdischarged from the clarifier tank 1850 (e.g., to the aeration tank ofthe existing wastewater treatment plant, as shown in FIG. 23).

During the pilot test of the system 1800, the first inline saturator1810 supplied oxygen saturated wastewater at a flowrate of between 20LPM and 60 LPM, such as 30 LPM (on average) and with dissolved oxygen ofbetween 30 ppm and 70 ppm, such as 62 ppm to the biological reactor1830. The pump 1840 recirculated wastewater from the biological reactor1830 to the second inline saturator 1820 at a flowrate of between 90 LPMand 150 LPM, such 150 LPM (or an average of 120 LPM), and the secondinline saturator 1820 supplied oxygen saturated wastewater at a flowrateof 90 LPM and 150 LPM, such as 150 LPM (or an average of 120 LPM) andwith dissolved oxygen of between 30 ppm and 70 ppm, such as 62 ppm, tothe biological reactor 1830. The biological reactor 1830 operated at ahydraulic retention time (HRT) of 7.2 hours (e.g., the amount of timethe wastewater remained in the biological reactor 1830 before beingdischarged therefrom). Wastewater flowed between the second inlinesaturator 1820 and the clarifier tank 1850 at a flowrate of 60 LPM, aflow of 30 LPM was recirculated by the recirculation pump 1860 from theclarifier tank 1850 to the second inline saturator 1820, and a flow of30 LPM of final effluent was discharged from the clarifier tank 1850(e.g., to the aeration tank of the existing wastewater treatment plant).The clarifier tank 1850 also operated at a hydraulic retention time(HRT) of 7.2 hours. The first inline saturator 1810 and the secondinline saturator 1820 operated at pressures of between 20 psi and 30 psi(e.g., an average of 25 psi).

As shown in FIG. 24, the system 1800 advantageously achieved a 95%reduction in BOD in the effluent flow, exceeding the required 80%removal target. Once the system 1800 achieved steady state of operation,it achieved an 87% reduction in BOD in the effluent flow (exceeding therequired 80% removal target), up from an initial 44% reduction when thesystem 1800 was initially put into operation. The improved 95% reductionin BOD in the effluent flow was achieved following, among othermodification, an increase in the HRT to that shown in FIG. 22, and theincrease in recirculation flowrate to the second inline saturator 1820shown in FIG. 22. In another implementation, the first inline saturator1810 can be excluded and only the second inline saturator 1820 can beoperated in the system 1800 to provide oxygen saturated wastewater tothe biological reactor 1830. It will be appreciated that an optimizedgas infusion system for an wastewater aeration system utilizing abalanced arrangement of gas infusion modules may achieve the oxygenlevels per kilowatt hour obtained in the disclosure herein. The gasinfusion modules and gas infusion systems (e.g., gas infusion units)described herein provide various advantages in the treatment ofwastewater. For example, because infusion of wastewater with oxygenoccurs in a bubble-free gas transfer manner, less oxygen is lost to theenvironment from bubbles breaking the surface tension of the aerationtank, allowing the saturation of wastewater with oxygen to improve thebiological process in the aeration tank (e.g., biological reactor), suchas by more efficient oxygenation and use of available oxygen. As aresult, a significant reduction in power (e.g., by as much as 50%, 60%or more) is achieved as air blowers and other equipment typically usesin wastewater treatment plants for the aeration process can be replacedand/or augmented with gas infusion systems described herein.Additionally, the gas infusion systems and modules described hereinadvantageously achieve a reduction of biochemical oxygen demand (BOD)(e.g., up to 95%, as shown in FIG. 24), allow for a reduced footprintfor blower requirements, thereby reducing plant size and capitalexpenditures. Further, the gas infusion systems and modules describedherein advantageously provide a wastewater treatment plan withflexibility to increase oxygen to meet increased demand. Additionally,the modular construction of the gas infusion systems (e.g., ability touse multiple gas infusion units, for example, in parallel) facilitatesexpansion of plant capacity.

ADDITIONAL EMBODIMENTS

In embodiments of the present disclosure, an augment system for anacetabular cup may be in accordance with any of the following clauses:

Clause 1. A wastewater oxygenation system, comprising:

-   -   an oxygen source configured to supply pressurized oxygen of at        least 70% purity; and    -   an oxygen infusion system comprising one or more oxygen infusion        modules, each oxygen infusion module comprising a housing, a        plurality of hydrophobic hollow microporous fibers disposed in        the housing, each of the hydrophobic hollow microporous fibers        having a longitudinal bore and a plurality of micropores on a        circumferential wall about the longitudinal bore, each oxygen        infusion module being in fluid communication with the oxygen        source so that the plurality of hydrophobic hollow microporous        fibers receive the pressurized oxygen from the oxygen source        through the longitudinal bore thereof,    -   wherein the oxygen infusion system is configured to receive a        flow of wastewater from a wastewater supply line such that the        wastewater flows through each of the one or more oxygen infusion        modules and comes in contact with the circumferential wall of        one or more of the plurality of hydrophobic hollow microporous        fibers so that the pressurized oxygen is transferred to the        wastewater through the plurality of micropores such that oxygen        transfer to the wastewater occurs free of oxygen bubbles in the        wastewater, the oxygenated wastewater discharged from the oxygen        infusion system via a wastewater output connection.

Clause 2. The system of Clause 1, wherein the oxygen source is an oxygengenerator configured to receive atmospheric air via an air intake.

Clause 3. The system of any preceding clause, wherein the microporeshave a pore pathway diameter of between about 0.01 μm to about 5 μm.

Clause 4. The system of any preceding clause, wherein each of theplurality of hydrophobic hollow microporous fibers has a length ofbetween about 9 inches and about 13 inches.

Clause 5. The system of any preceding clause, wherein the plurality ofhydrophobic hollow microporous fibers has a packing factor within thehousing of the oxygen infusion module of no more than approximately 38%.

Clause 6. The system of any preceding clause, wherein the plurality ofhydrophobic hollow microporous fibers for each of the one or more oxygeninfusion modules has a porosity of 75%.

Clause 7. The system of any preceding clause, wherein the plurality ofhydrophobic hollow microporous fibers of each oxygen infusion module arewoven into a mat configured to be rolled and disposed in the housing ofthe oxygen infusion module.

Clause 8. The system of any preceding clause, further comprising ahousing that houses the oxygen source and the oxygen infusion system toprovide a standalone gas infusion unit.

Clause 9. The system of Clause 8, wherein the housing that houses theoxygen source and the oxygen infusion system is a shipping containerwith a length of 20 feet to 40 feet.

Clause 10. The system of any preceding clause, wherein the wastewaterand pressurized oxygen flow through the one or more gas infusion modulesin a co-current manner.

Clause 11. The system of any preceding clause, wherein the oxygeninfusion system includes housing that houses the one or more oxygeninfusion modules.

Clause 12. The system of any preceding clause, wherein the one or moreoxygen infusion modules are a plurality of oxygen infusion modulesarranged in parallel so that the wastewater flows through the pluralityof oxygen infusion modules in parallel and so that the pressurizedoxygen flows through the plurality of oxygen infusion modules inparallel.

Clause 13. The system of Clause 12, wherein the plurality of oxygeninfusion modules arranged in parallel are housed in a gas infusion tank.

Clause 14. The system of any preceding clause, wherein the one or moreoxygen infusion modules include a first array of a plurality of oxygeninfusion modules arranged in parallel and a second array of a pluralityof oxygen infusion modules arranged in parallel, the second arrayarranged in series with the first array, so that the wastewater flows inparallel through the plurality of oxygen infusion modules of each of thefirst array and the second array, so that the pressurized oxygen flowsin parallel through the plurality of oxygen infusion modules of the eachof the first array and the second array, and so that the wastewaterflows through the second array after it flows through the first array.

Clause 15. The system of Clause 14, wherein the first array of oxygeninfusion modules is spaced vertically above the second array of oxygeninfusion modules.

Clause 16. The system of any of Clauses 14-15, wherein the pressurizedoxygen is introduced into the plurality of oxygen infusion modules via agap between a pair of plates disposed above the plurality of oxygeninfusion modules, said gap facilitating delivery of the pressurizedoxygen at the same pressure and flowrate through the plurality of oxygeninfusion modules.

Clause 17. The system of any preceding clause, further comprising acontroller configured to control one or both of the flow of wastewaterand the flow of pressurized oxygen through the one or more gas infusionmodules.

Clause 18. The system of Clause 1, wherein the one or more oxygeninfusion modules includes a first oxygen infusion module and a secondoxygen infusion module, the second oxygen infusion module arranged inseries with the first oxygen infusion module so that wastewater flowsthrough the first oxygen infusion module and then flows through thesecond oxygen infusion module.

Clause 19. The system of any preceding clause, further comprising a gasvent configured to vent undissolved oxygen and nitrogen from the oxygeninfusion system.

Clause 20. The system of any preceding clause, wherein the housing ofeach oxygen infusion module includes one or more openings in a sidewallof the housing via which wastewater enters the oxygen infusion module.

Clause 21. The system of Clause 20, wherein the one or more openings area pair of openings on opposite sides of the housing.

Clause 22. A wastewater oxygenation system, comprising:

-   -   a tank having a cover with an inlet opening configured to        receive a flow of wastewater therethrough, and a tank vessel        disposed below the cover, the tank vessel having an outlet        opening at a distal end of the tank vessel; and    -   a plurality of oxygen infusion modules arranged in parallel and        disposed in the tank vessel below the cover, each oxygen        infusion module comprising        -   a housing, and        -   a plurality of hydrophobic hollow microporous fibers            disposed in the housing, each of the hydrophobic hollow            microporous fibers having a longitudinal bore and a            plurality of micropores on a circumferential wall about the            longitudinal bore,    -   wherein each of the oxygen infusion modules is configured to        receive a portion of the flow of wastewater such that the        wastewater comes in contact with the circumferential wall of one        or more of the plurality of hydrophobic hollow microporous        fibers, and wherein each of the oxygen infusion modules is        configured to receive a flow of pressurized oxygen so that the        pressurized oxygen is transferred to the wastewater through the        plurality of micropores such that oxygen transfer to the        wastewater occurs free of oxygen bubbles in the wastewater, and        wherein the wastewater flows through the plurality of oxygen        infusion modules in parallel and so that the pressurized oxygen        flows through the plurality of oxygen infusion modules in        parallel, the oxygenated wastewater discharged from the tank via        the outlet opening in the tank vessel.

Clause 23. The system of Clause 22, wherein the micropores have a porepathway diameter of between about 0.01 μm to about 5 μm.

Clause 24. The system of any of Clauses 22-23, wherein each of theplurality of hydrophobic hollow microporous fibers has a length ofbetween about 9 inches and about 13 inches.

Clause 25. The system of any of Clauses 22-24, wherein the plurality ofhydrophobic hollow microporous fibers has a packing factor within thehousing of the oxygen infusion module of no more than approximately 38%.

Clause 26. The system of any of Clauses 22-25, wherein the plurality ofhydrophobic hollow microporous fibers for each of the oxygen infusionmodules has a porosity of 75%.

Clause 27. The system of any of Clauses 22-26, wherein the plurality ofhydrophobic hollow microporous fibers of each oxygen infusion module arewoven into a mat configured to be rolled and disposed in the housing ofthe oxygen infusion module.

Clause 28. The system of any of Clauses 22-27, wherein the wastewaterand the pressurized oxygen flow through the gas infusion modules in aco-current manner.

Clause 29. The system of any of Clauses 22-28, wherein the plurality ofoxygen infusion modules arranged in parallel include a first array ofoxygen infusion modules arranged in parallel and a second array ofoxygen infusion modules arranged in parallel, the second array arrangedin series with the first array so that the wastewater flows in parallelthrough the oxygen infusion modules of each of the first array and thesecond array, so that the pressurized oxygen flows in parallel throughthe oxygen infusion modules of the each of the first array and thesecond array, and so that the wastewater flows through the second arrayafter it flows through the first array.

Clause 30. The system of Clause 29, wherein the first array of oxygeninfusion modules is spaced vertically above the second array of oxygeninfusion modules.

Clause 31. The system of any of Clauses 29-30, wherein the pressurizedoxygen is introduced into the plurality of oxygen infusion modules via agap between a pair of plates disposed above the plurality of oxygeninfusion modules, said gap facilitating delivery of the pressurizedoxygen at the same pressure and flowrate through the plurality of oxygeninfusion modules.

Clause 32. The system of any of Clauses 22-31, further comprising acontroller configured to control one or both of the flow of wastewaterand the flow of pressurized oxygen through the one or more gas infusionmodules.

Clause 33. The system of any of Clauses 22-32, further comprising a gasvent configured to vent undissolved oxygen and nitrogen from the oxygeninfusion system.

Clause 34. The system of any of Clauses 22-33, wherein the housing ofeach oxygen infusion module includes one or more openings in a sidewallof the housing via which wastewater enters the oxygen infusion module.

Clause 35. The system of Clause 34, wherein the one or more openings area pair of openings on opposite sides of the housing.

Clause 36. A wastewater oxygenation system, comprising:

-   -   a tank having a cover with an inlet opening configured to        receive a flow of wastewater therethrough, and a tank vessel        disposed below the cover, the tank vessel having an outlet        opening at a distal end of the tank vessel;    -   a first array of oxygen infusion modules arranged in parallel        and disposed in the tank vessel below the cover; and    -   a second array of oxygen infusion modules arranged in parallel        and disposed in the tank vessel, the second array spaced below        the first array so that the second array is in series with the        first array,    -   each oxygen infusion module in the first array and the second        array comprising        -   a housing, and        -   a plurality of hydrophobic hollow microporous fibers            disposed in the housing, each of the hydrophobic hollow            microporous fibers having a longitudinal bore and a            plurality of micropores on a circumferential wall about the            longitudinal bore,    -   wherein each of the oxygen infusion modules is configured to        receive a portion of the flow of wastewater such that the        wastewater comes in contact with the circumferential wall of one        or more of the plurality of hydrophobic hollow microporous        fibers, and wherein each of the oxygen infusion modules is        configured to receive a flow of pressurized oxygen so that the        pressurized oxygen is transferred to the wastewater through the        plurality of micropores such that oxygen transfer to the        wastewater occurs free of oxygen bubbles in the wastewater, and        wherein the wastewater flows in parallel through the oxygen        infusion modules of each of the first array and the second        array, the pressurized oxygen flows in parallel through the        oxygen infusion modules of the each of the first array and the        second array, and the wastewater flows through the second array        after it flows through the first array, the oxygenated        wastewater discharged from the tank via the outlet opening in        the tank vessel.

Clause 37. The system of Clause 36, wherein the micropores have a porepathway diameter of between about 0.01 μm to about 5 μm.

Clause 38. The system of any of Clauses 36-37, wherein each of theplurality of hydrophobic hollow microporous fibers has a length ofbetween about 9 inches and about 13 inches.

Clause 39. The system of any of Clauses 36-38, wherein the plurality ofhydrophobic hollow microporous fibers has a packing factor within thehousing of the oxygen infusion module of no more than approximately 38%.

Clause 40. The system of any of Clauses 36-39, wherein the plurality ofhydrophobic hollow microporous fibers for each of the oxygen infusionmodules has a porosity of 75%.

Clause 41. The system of any of Clauses 36-40, wherein the plurality ofhydrophobic hollow microporous fibers of each oxygen infusion module arewoven into a mat configured to be rolled and disposed in the housing ofthe oxygen infusion module.

Clause 42. The system of any Clauses 36-41, wherein the wastewater andthe pressurized oxygen flow through the gas infusion modules in aco-current manner.

Clause 43. The system of any of Clauses 36-42, wherein the first arrayof oxygen infusion modules is spaced vertically above the second arrayof oxygen infusion modules.

Clause 44. The system of any of Clauses 36-43, wherein the pressurizedoxygen is introduced into the plurality of oxygen infusion modules ineither of the first array and second array via a gap between a pair ofplates disposed above the plurality of oxygen infusion modules, said gapfacilitating delivery of the pressurized oxygen at the same pressure andflowrate through the plurality of oxygen infusion modules.

Clause 45. The system of any of Clauses 36-44, further comprising acontroller configured to control one or both of the flow of wastewaterand the flow of pressurized oxygen through the one or more gas infusionmodules.

Clause 46. The system of any of Clauses 36-45, further comprising a gasvent configured to vent undissolved oxygen and nitrogen from the oxygeninfusion system, the gas vent in fluid communication with a fitting on asidewall of the tank vessel and with a siphon break tube coupled to theoutlet opening.

Clause 47. The system of any of Clauses 36-46, wherein the housing ofeach oxygen infusion module includes one or more openings in a sidewallof the housing via which wastewater enters the oxygen infusion module.

Clause 48. The system of Clause 47, wherein the one or more openings area pair of openings on opposite sides of the housing.

Clause 49. An oxygen infusion module, comprising:

-   -   a housing;    -   a central tube that extends along an axis of the housing;    -   a top plug attached to a proximal end of the housing;    -   a bottom plug attached to a distal end of the housing;    -   a plurality of hydrophobic hollow microporous fibers disposed in        the housing and suspended from a disc and arranged about the        central tube, the hydrophobic hollow microporous fibers having a        length shorter than a length of the housing, each of the        hydrophobic hollow microporous fibers having a longitudinal bore        and a plurality of micropores on a circumferential wall about        the longitudinal bore; and    -   a vent in fluid communication with the central tube and with a        space inside the housing about the central tube, the vent being        configured to vent undissolved oxygen and nitrogen from the        oxygen infusion module,    -   wherein the oxygen infusion module is configured to receive a        flow of pressurized oxygen from an oxygen source so that the        plurality of hydrophobic hollow microporous fibers receive the        pressurized oxygen from the oxygen source through the        longitudinal bore thereof,    -   wherein the oxygen infusion module is configured to receive a        flow of wastewater such that the wastewater flows through the        central tube and into the housing so that it comes in contact        with the circumferential wall of one or more of the plurality of        hydrophobic hollow microporous fibers so that the pressurized        oxygen is transferred to the wastewater through the plurality of        micropores such that oxygen transfer to the wastewater occurs        free of oxygen bubbles in the wastewater, the oxygenated        wastewater discharged from the housing via one or more distal        openings and via the bottom plug.

Clause 50. The module of Clause 49, wherein the micropores have a porepathway diameter of between about 0.01 μm to about 5 μm.

Clause 51. The module of any of Clauses 49-50, wherein each of theplurality of hydrophobic hollow microporous fibers has a length ofbetween about 9 inches and about 13 inches.

Clause 52. The module of any of Clauses 49-51, wherein the plurality ofhydrophobic hollow microporous fibers has a packing factor within thehousing of the oxygen infusion module of no more than approximately 38%.

Clause 53. The module of any of Clauses 49-52, wherein the plurality ofhydrophobic hollow microporous fibers for each of the oxygen infusionmodules has a porosity of 75%.

Clause 54. The module of any of Clauses 49-53, wherein the plurality ofhydrophobic hollow microporous fibers of each oxygen infusion module arewoven into a mat configured to be rolled and disposed in the housing ofthe oxygen infusion module.

Clause 55. The module of any of Clauses 49-54, wherein the wastewaterand the pressurized oxygen flow through the gas infusion modules in aco-current manner.

Clause 56. An oxygen infusion module, comprising:

-   -   a housing with one or more openings on a sidewall of the housing        via which wastewater enters the housing; and    -   a plurality of hydrophobic hollow microporous fibers disposed in        the housing and suspended from a disc, each of the hydrophobic        hollow microporous fibers having a longitudinal bore and a        plurality of micropores on a circumferential wall about the        longitudinal bore,    -   wherein the oxygen infusion module is configured to receive a        flow of pressurized oxygen from an oxygen source so that the        plurality of hydrophobic hollow microporous fibers receive the        pressurized oxygen from the oxygen source through the        longitudinal bore thereof,    -   wherein the oxygen infusion module is configured to receive a        flow of wastewater via the one or more openings in the sidewall        of the housing such that the wastewater comes in contact with        the circumferential wall of one or more of the plurality of        hydrophobic hollow microporous fibers so that the pressurized        oxygen is transferred to the wastewater through the plurality of        micropores such that oxygen transfer to the wastewater occurs        free of oxygen bubbles in the wastewater, the oxygenated        wastewater discharged from the housing via a distal end of the        housing.

Clause 57. The module of Clause 56, wherein the micropores have a porepathway diameter of between about 0.01 μm to about 5 μm.

Clause 58. The module of any of Clauses 56-57, wherein each of theplurality of hydrophobic hollow microporous fibers has a length ofbetween about 9 inches and about 13 inches.

Clause 59. The module of any of Clauses 56-58, wherein the plurality ofhydrophobic hollow microporous fibers has a packing factor within thehousing of the oxygen infusion module of no more than approximately 38%.

Clause 60. The module of any of Clauses 56-59, wherein the plurality ofhydrophobic hollow microporous fibers for each of the oxygen infusionmodules has a porosity of 75%.

Clause 61. The module of any of Clauses 56-60, wherein the plurality ofhydrophobic hollow microporous fibers of each oxygen infusion module arewoven into a mat configured to be rolled and disposed in the housing ofthe oxygen infusion module.

Clause 62. The module of any of Clauses 56-61, wherein the wastewaterand the pressurized oxygen flow through the gas infusion modules in aco-current manner.

Clause 63. The module of any of Clauses 56-62, wherein the one or moreopenings are a pair of openings on opposite sides of the housing.

Clause 64. A method of oxygenating wastewater for use aerobic wastewatertreatment, comprising:

-   -   generating a supply of pressurized oxygen using an oxygen        generator, wherein the oxygen concentration is at least 70%;    -   supplying the pressurized oxygen to a first gas infusion system        comprising one or more gas infusion modules, each gas infusion        module comprising a housing, a plurality of hydrophobic hollow        microporous fibers disposed in the housing, each of the        hydrophobic hollow microporous fibers having a longitudinal bore        and a plurality of micropores on a circumferential wall about        the longitudinal bore, each gas infusion module being in fluid        communication with the oxygen generator so that the pressurized        oxygen is supplied to the plurality of hydrophobic hollow        microporous fibers through the longitudinal bore thereof;    -   supplying a flow of wastewater to the one or more gas infusion        modules such that the wastewater flows through each of the one        or more gas infusion modules and comes in contact with the        circumferential wall of one or more of the plurality of        hydrophobic hollow microporous fibers so that the pressurized        oxygen is transferred to the wastewater through the plurality of        micropores such that oxygen transfer to the wastewater occurs        free of oxygen bubbles in the wastewater to form a        supersaturated effluent having a level of oxygen concentration        above 62 ppm; and    -   discharging the supersaturated effluent to an aeration        reservoir.

Clause 65. The method of Clause 64, wherein the micropores have a porepathway diameter of between about 0.01 μm to about 5 μm.

Clause 66. The method of any of Clause 64-65, wherein each of theplurality of hydrophobic hollow microporous fibers has a length ofbetween about 9 inches and about 13 inches.

Clause 67. The method of any of Clauses 64-66, wherein the plurality ofhydrophobic hollow microporous fibers has a packing factor within thehousing of the gas infusion module of no more than approximately 38%.

Clause 68. The method of any of Clauses 64-67, wherein the plurality ofhydrophobic hollow microporous fibers for each of the one or more gasinfusion modules has a porosity of 75%.

Clause 69. The method of any of Clauses 64-68, wherein the plurality ofhydrophobic hollow microporous fibers of each gas infusion module arewoven into a mat configured to be rolled and disposed in the housing ofthe gas infusion module.

Clause 70. The method of any of Clauses 64-69, further comprising:

-   -   supplying the pressurized oxygen to a second gas infusion system        wherein the second gas infusion system comprises one or more gas        infusion modules, each gas infusion module comprising a housing,        a plurality of hydrophobic hollow microporous fibers disposed in        the housing, each of the hydrophobic hollow microporous fibers        having a longitudinal bore and a plurality of micropores on a        circumferential wall about the longitudinal bore, each gas        infusion module being in fluid communication with the oxygen        generator so that the pressurized oxygen is supplied to the        plurality of hydrophobic hollow microporous fibers through the        longitudinal bore thereof;    -   supplying effluent from the aeration reservoir to the one or        more gas infusion modules of the second gas infusion system such        that the effluent flows through each of the one or more gas        infusion modules and comes in contact with the circumferential        wall of one or more of the plurality of hydrophobic hollow        microporous fibers so that the pressurized oxygen is transferred        to the effluent through the plurality of micropores such that        oxygen transfer to the wastewater occurs free of oxygen bubbles        in the wastewater to form a supersaturated effluent having a        level of oxygen concentration above 62 ppm; and    -   discharging the supersaturated effluent to the aeration        reservoir.

Clause 71. The method of Clause 70 further comprising:

-   -   discharging wastewater from the aeration reservoir wherein a        biological process in the aeration reservoir achieved a level of        approximately 0.9 Kg0₂/Kg BOD.

Clause 72. The method of Clause 70 wherein the wastewater is dischargedinto the aeration reservoir such that a power demand of a wastewatertreatment process is between 0.16 KWH/m³ wastewater treated and 0.75KWH/m³ sewage treated.

Clause 73. The method of Clause 70 wherein the wastewater is dischargedinto the aeration reservoir such that a power demand of a wastewatertreatment process is approximately 0.35 KWH/m³ wastewater treated.

Clause 74. The method of any of Clauses 64-73, further comprisingsupplying one or more gases to the first gas infusion system aftersupplying the pressurized oxygen to the first gas infusion system, theone or more gases configured to flow through the hydrophobic hollowmicroporous fibers in the housing and come in contact with thewastewater flowing through the one or more gas infusion modules via theplurality of micropores in order to replace the oxygen in the wastewaterwith the one or more gases, the one or more gases transferred to thewastewater free of bubbles.

Clause 75. The method of Clause 74, wherein the one or more gases is amixed gas.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms. Furthermore, various omissions, substitutions and changes in thesystems and methods described herein may be made without departing fromthe spirit of the disclosure. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the disclosure. Accordingly, thescope of the present inventions is defined only by reference to theappended claims.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example described inthis section or elsewhere in this specification unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The protection is notrestricted to the details of any foregoing embodiments. The protectionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as a subcombination or variation of asubcombination.

Moreover, while operations may be depicted in the drawings or describedin the specification in a particular order, such operations need not beperformed in the particular order shown or in sequential order, or thatall operations be performed, to achieve desirable results. Otheroperations that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the described operations. Further, the operations may berearranged or reordered in other implementations. Those skilled in theart will appreciate that in some embodiments, the actual steps taken inthe processes illustrated and/or disclosed may differ from those shownin the figures. Depending on the embodiment, certain of the stepsdescribed above may be removed, others may be added. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure. Also, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the describedcomponents and systems can generally be integrated together in a singleproduct or packaged into multiple products.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. Not necessarily all such advantages maybe achieved in accordance with any particular embodiment. Thus, forexample, those skilled in the art will recognize that the disclosure maybe embodied or carried out in a manner that achieves one advantage or agroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements, and/or steps areincluded or are to be performed in any particular embodiment.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than 10% of, within less than 5% of, within less than 1% of, withinless than 0.1% of, and within less than 0.01% of the stated amount. Asanother example, in certain embodiments, the terms “generally parallel”and “substantially parallel” refer to a value, amount, or characteristicthat departs from exactly parallel by less than or equal to 15 degrees,10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

The scope of the present disclosure is not intended to be limited by thespecific disclosures of preferred embodiments in this section orelsewhere in this specification, and may be defined by claims aspresented in this section or elsewhere in this specification or aspresented in the future. The language of the claims is to be interpretedbroadly based on the language employed in the claims and not limited tothe examples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive.

Of course, the foregoing description is that of certain features,aspects and advantages of the present invention, to which variouschanges and modifications can be made without departing from the spiritand scope of the present invention. Moreover, the devices describedherein need not feature all of the objects, advantages, features andaspects discussed above. Thus, for example, those of skill in the artwill recognize that the invention can be embodied or carried out in amanner that achieves or optimizes one advantage or a group of advantagesas taught herein without necessarily achieving other objects oradvantages as may be taught or suggested herein. In addition, while anumber of variations of the invention have been shown and described indetail, other modifications and methods of use, which are within thescope of this invention, will be readily apparent to those of skill inthe art based upon this disclosure. It is contemplated that variouscombinations or subcombinations of these specific features and aspectsof embodiments may be made and still fall within the scope of theinvention. Accordingly, it should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thediscussed devices.

What is claimed is:
 1. An oxygen infusion module, comprising: a housing;a central tube that extends along an axis of the housing; a top plugattached to a proximal end of the housing; a bottom plug attached to adistal end of the housing; a plurality of hydrophobic hollow microporousfibers disposed in the housing and suspended from a disc and arrangedabout the central tube, the hydrophobic hollow microporous fibers havinga length shorter than a length of the housing, each of the hydrophobichollow microporous fibers having a longitudinal bore and a plurality ofmicropores on a circumferential wall about the longitudinal bore; and avent in fluid communication with the central tube and with a spaceinside the housing about the central tube, the vent being configured tovent undissolved oxygen and nitrogen from the oxygen infusion module,wherein the oxygen infusion module is configured to receive a flow ofpressurized oxygen from an oxygen source so that the plurality ofhydrophobic hollow microporous fibers receive the pressurized oxygenfrom the oxygen source through the longitudinal bore thereof, whereinthe oxygen infusion module is configured to receive a flow of wastewatersuch that the wastewater flows through the central tube and into thehousing so that it comes in contact with the circumferential wall of oneor more of the plurality of hydrophobic hollow microporous fibers sothat the pressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater, the oxygenatedwastewater discharged from the housing via one or more distal openingsand via the bottom plug.
 2. The module of claim 1, wherein themicropores have a pore pathway diameter of between about 0.01 μm toabout 5 μm.
 3. The module of claim 1, wherein each of the plurality ofhydrophobic hollow microporous fibers has a length of between about 9inches and about 13 inches.
 4. The module of claim 1, wherein theplurality of hydrophobic hollow microporous fibers has a packing factorwithin the housing of the oxygen infusion module of no more thanapproximately 38%.
 5. The module of claim 1, wherein the plurality ofhydrophobic hollow microporous fibers for each of the oxygen infusionmodules has a porosity of 75%.
 6. The module of claim 1, wherein theplurality of hydrophobic hollow microporous fibers of each oxygeninfusion module are woven into a mat configured to be rolled anddisposed in the housing of the oxygen infusion module.
 7. The module ofclaim 1, wherein the wastewater and the pressurized oxygen flow throughthe oxygen infusion modules in a co-current manner.
 8. An oxygeninfusion module, comprising: a housing with one or more openings on asidewall of the housing via which wastewater enters the housing; and aplurality of hydrophobic hollow microporous fibers disposed in thehousing and suspended from a disc, each of the hydrophobic hollowmicroporous fibers having a longitudinal bore and a plurality ofmicropores on a circumferential wall about the longitudinal bore,wherein the oxygen infusion module is configured to receive a flow ofpressurized oxygen from an oxygen source so that the plurality ofhydrophobic hollow microporous fibers receive the pressurized oxygenfrom the oxygen source through the longitudinal bore thereof, whereinthe oxygen infusion module is configured to receive a flow of wastewatervia the one or more openings in the sidewall of the housing such thatthe wastewater comes in contact with the circumferential wall of one ormore of the plurality of hydrophobic hollow microporous fibers so thatthe pressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater, the oxygenatedwastewater discharged from the housing via a distal end of the housing.9. The module of claim 8, wherein the micropores have a pore pathwaydiameter of between about 0.01 μm to about 5 μm.
 10. The module of claim8, wherein each of the plurality of hydrophobic hollow microporousfibers has a length of between about 9 inches and about 13 inches. 11.The module of claim 8, wherein the plurality of hydrophobic hollowmicroporous fibers has a packing factor within the housing of the oxygeninfusion module of no more than approximately 38%.
 12. The module ofclaim 8, wherein the plurality of hydrophobic hollow microporous fibersfor each of the oxygen infusion modules has a porosity of 75%.
 13. Themodule of claim 8, wherein the plurality of hydrophobic hollowmicroporous fibers of each oxygen infusion module are woven into a matconfigured to be rolled and disposed in the housing of the oxygeninfusion module.
 14. The module of claim 8, wherein the wastewater andthe pressurized oxygen flow through the oxygen infusion modules in aco-current manner.
 15. The module of claim 8, wherein the one or moreopenings are a pair of openings on opposite sides of the housing.
 16. Anoxygen infusion module, comprising: a housing with a plurality ofopenings on a sidewall of the housing via which wastewater enters thehousing; and a plurality of hydrophobic hollow microporous fibersdisposed in the housing and suspended from a disc, each of thehydrophobic hollow microporous fibers having a longitudinal bore and aplurality of micropores on a circumferential wall about the longitudinalbore, wherein the oxygen infusion module is configured to receive a flowof pressurized oxygen from an oxygen source so that the plurality ofhydrophobic hollow microporous fibers receive the pressurized oxygenfrom the oxygen source through the longitudinal bore thereof, whereinthe oxygen infusion module is configured to receive a flow of wastewatervia the one or more openings in the sidewall of the housing such thatthe wastewater comes in contact with the circumferential wall of one ormore of the plurality of hydrophobic hollow microporous fibers so thatthe pressurized oxygen is transferred to the wastewater through theplurality of micropores such that oxygen transfer to the wastewateroccurs free of oxygen bubbles in the wastewater, the oxygenatedwastewater discharged from the housing via a distal end of the housing.17. The module of claim 17, wherein the micropores have a pore pathwaydiameter of between about 0.01 μm to about 5 μm.
 18. The module of claim17, wherein each of the plurality of hydrophobic hollow microporousfibers has a length of between about 9 inches and about 13 inches. 19.The module of claim 17, wherein the plurality of hydrophobic hollowmicroporous fibers has a packing factor within the housing of the oxygeninfusion module of no more than approximately 38%.
 20. The module ofclaim 17, wherein the plurality of hydrophobic hollow microporous fibersfor each of the oxygen infusion modules has a porosity of 75%.
 21. Themodule of claim 17, wherein the plurality of hydrophobic hollowmicroporous fibers of each oxygen infusion module are woven into a matconfigured to be rolled and disposed in the housing of the oxygeninfusion module.
 22. The module of claim 17, wherein the wastewater andthe pressurized oxygen flow through the oxygen infusion modules in aco-current manner.